.editrc on linux.

MySQL client when build with libedit support ignores
.editrc at startup.

The reason for this regression was the incluison of a
safety check, issetugid(), which is not available on
some linux platforms.

Fixed by adding an equivalent check for platforms which
have get[e][u|g]id() set of functions.

BEFORE: First packet sent by client-side plugin (generated by Windows
function InitializeSecurityContext()) could be longer than 255 bytes 
violating the limitation imposed by authentication protocol.

AFTER: Handshake protocol is  changed so that if first client's reply is 
longer than 254 bytes then  it is be sent in 2 parts. However, for replies
shorter than 255 bytes nothing changes.

ADDITIONAL CHANGES: 
- The generic packet processing loop  (Handshake::packet_processing_loop) 
has been refactored. Communication with the peer has been abstracted
into virtual methods read/write_packet() which are implemented in client 
and server and transparently do the required splitting and gluing of packets.
- Make it possible to optionally use dbug library in the plugin.
- Add code for testing splitting of long first client reply.

into the server repository

This patch adds client windows authentication plugin code to the client 
library libmysql (only on Windows platform). The plugin is compiled into 
the library and added to the list of built-in plugins. This way clients 
should be able to connect to a server which uses windows authentication 
plugin even as an SQL user which uses such authentication.

Note: this makes the client library to depend on Secur32 Windows system
library. When building clients, they must be linked against Secur32. 
Command mysql_config --libs correctly lists Secur32 as a required 
dependency.

Removed STDCALL from the function definition.

Enabled the ABI check to run on MacOSX.

Partitions can have different ref_length (position data length).
Removed DBUG_ASSERT which crashed debug builds when using
MAX_ROWS on some partitions.

               FAILS WITH LIBEDIT

Fixed by checking the return value of the write()
function calls and handling the open files and fd
appropriately.

 - fix the fix to properly detect when engine is NDB and
   also don't drop the table t9 if it hasn't been created

Fix: it only worked if some worker had valgrind report from its last test
Flag has to be set both places where report is printed

calc_daynr() function returns negative result
if malformed date with zero year and month is used.
Attempt to calculate week day on negative value
leads to crash. The fix is return NULL for
'W', 'a', 'w' specifiers if zero year and month is used.
Additional fix for calc_daynr():
--added assertion that result can not be negative
--return 0 if zero year and month is used