Trying to run perl fails, just like it does when perl is started but fails
Trap the case that perl was not found/could not be started, and skip test
Also force a restart of servers since test may already have done something
mtr now also appends path of current perl to PATH to aid mysqltest

This happens when creating new tmpdir due to too long socket path
Don't delete it if --start-and-exit, but warn user to do it.

Adds boolean flag is_int and a separete function to check for int value
Added tests to mysqltest.test

Use UNINIT_VAR workaround instead of LINT_INIT. The former can
also be used to silence false-positives in non-debug builds as
it actually does not cause new code to be generated.

Use UNINIT_VAR workaround instead of LINT_INIT. The former is
also used in non-debug builds as it doesn't cause changes.

argument of inline_mysql_mutex_init in sql_base.cc.

When initializing LOCK_dd_owns_lock_open mutex pass
correct PSI key instead of NULL value.

Temporarily disable strict aliasing warnings in order to get
wider coverage for optimized builds. Once the violations are
fixed and false-positives silenced, this flag should be removed.

Added --enable-connect-log, somewhet similar to --enable-query-log
If query log is disabled, disable connect log too
Also some related cleanup in mysqltest.test: removing duplicate test loop

Null-merge from 5.1

Merge from saved bundle.

Follow-up: don't call pthread_join() on Windows
This change only valid for 5.1

Added counts of skipped test, inclusing how many by test itself
Also fixed misspelling in the (hitherto unused) variable name

The problem was that the x86 assembly based atomic CAS
(compare and swap) implementation could copy the wrong
value to the ebx register, where the cmpxchg8b expects
to see part of the "comparand" value. Since the original
value in the ebx register is saved in the stack (that is,
the push instruction causes the stack pointer to change),
a wrong offset could be used if the compiler decides to
put the source of the comparand value in the stack.

The solution is to copy the comparand value directly from
memory. Since the comparand value is 64-bits wide, it is
copied in two steps over to the ebx and ecx registers.

Subselect executes twice, at JOIN::optimize stage
and at JOIN::execute stage. At optimize stage
Innodb prebuilt struct which is used for the
retrieval of column values is initialized in.
ha_innobase::index_read(), prebuilt->sql_stat_start is true.
After QUICK_ROR_INTERSECT_SELECT finished his job it
restores read_set/write_set bitmaps with initial values
and deactivates one of the handlers used by
QUICK_ROR_INTERSECT_SELECT in JOIN::cleanup
(it's the case when we reuse original handler as one of
 handlers required by QUICK_ROR_INTERSECT_SELECT object).
On second subselect execution inactive handler is activated
in  QUICK_RANGE_SELECT::reset, file->ha_index_init().
In ha_index_init Innodb prebuilt struct is reinitialized
with inappropriate read_set/write_set bitmaps. Further
reinitialization in ha_innobase::index_read() does not
happen as prebuilt->sql_stat_start is false.
It leads to partial retrieval of required field values
and we get a mix of field values from different records
in the record buffer.
The fix is to reset
read_set/write_set bitmaps as these values
are required for proper intialization of
internal InnoDB struct which is used for
the retrieval of column values
(see build_template(), ha_innodb.cc)

           adding new indexes

A fast alter table requires that the existing (old) table
and indices are unchanged (i.e only new indices can be
added).  To verify this, the layout and flags of the old
table/indices are compared for equality with the new.

The PACK_KEYS option is a no-op in InnoDB, but the flag
exists, and is used in the table compare.  We need to
check this (table) option flag before deciding whether an 
index should be packed or not.  If the table has
explicitly set PACK_KEYS to 0, the created indices should
not be marked as packed/packable. 

compression protocol.

The loss of connection was caused by a malformed packet
sent by the server in case when query cache was in use.
When storing data in the query cache, the query  cache
memory allocation algorithm had a tendency to reduce
the amount of memory block necessary to store a result
set, up to finally storing the entire result set in a single
block. With a significant result set, this memory block
could turn out to be quite large - 30, 40 MB and on.
When such a result set was sent to the client, the entire
memory block was compressed and written to network as a
single network packet. However, the length of the
network packet is limited by 0xFFFFFF (16MB), since
the packet format only allows 3 bytes for packet length.
As a result, a malformed, overly large packet
with truncated length would be sent to the client
and break the client/server protocol.

The solution is, when sending result sets from the query
cache, to ensure that the data is chopped into
network packets of size <= 16MB, so that there
is no corruption of packet length. This solution,
however, has a shortcoming: since the result set
is still stored in the query cache as a single block,
at the time of sending, we've lost boundaries of individual
logical packets (one logical packet = one row of the result
set) and thus can end up sending a truncated logical
packet in a compressed network packet.

As a result, on the client we may require more memory than 
max_allowed_packet to keep, both, the truncated
last logical packet, and the compressed next packet.
This never (or in practice never) happens without compression,
since without compression it's very unlikely that
a) a truncated logical packet would remain on the client
when it's time to read the next packet
b) a subsequent logical packet that is being read would be
so large that size-of-new-packet + size-of-old-packet-tail >
max_allowed_packet.
To remedy this issue, we send data in 1MB sized packets,
that's below the current client default of 16MB for
max_allowed_packet, but large enough to ensure there is no
unnecessary overhead from too many syscalls per result set.