Reason for the error was that ./configure wrapper script was  not 
safe for VPATH builds used by "make distcheck", specifically it expected configure.am to be in the current directory.

Fix changes configure wrapper to resolve script names relative 
to configure script path.

Also, use $top_srcdir/configure.am instead of configure.am in dist-hook to be more VPATH friendly.

    Plugins included into bin release cannot be
    installed on debug version of server

IF    the build process was split into separate "debug" and
      "optimized" builds
   AND
      the plugin files of the debug build got copied into
      "plugin/debug/"
(both is done for MySQL release builds starting from 5.5.3),
THEN these debug plugin files are to be included in the
     final binary package.

This change deals with the inclusion only,
the other parts are done in different changesets.

This is a fix specific for HPUX,
for which the compiler does not resolve properly dependencies
involving unused inline functions.
(See existing comments in mysql_thread.h)

In include/mysql/psi/mysql_thread.h,
the instrumentation helpers for mysql_prlock_*
uses the pr lock apis.

These apis are implemented in mysys/thr_rwlock.c,
which is not linked to client code.

As a result, the code does not link in libmysql_r, on HPUX.

The fix is to cut dependencies explicitely,
by introducing -DDISABLE_MYSQL_RWLOCK_H,
when building client code.

Ensure that we store the correct cached_field_type whenever we cache Field items
(in this case it allows us to compare dates as dates, rather than strings)

Before this fix, client tools (mysql_upgrade, mysqlcheck, mysqldump)
would try to process performance schema tables, leading to failures.

The fix is to align FIRST_PERFORMANCE_SCHEMA_VERSION to 5.5.3,
which is the version number of mysql-trunk where the
performance schema is first available.

Before this fix, the performance schema instrumentation
in mdl.h / mdl.cc was incomplete, causing:
- build warnings,
- no data collection for the performance schema

This fix:
- added instrumentation helpers for the new preferred
  reader read write lock, mysql_prlock_*
- implemented completely the performance schema
  instrumentation of mdl.h / mdl.cc

Set $glob_bindir, like $bindir in v2
Removed some obsolete IM code rather than changing it

Before this fix, mysql_upgrade would always drop and re create
the performance_schema database.
This in theory could destroy user data created using 5.1 or older versions.

With this fix, mysql_upgrade checks the content of the
performance_schema database before droping it.

Fix for BUG#51215 "log-error partially works with version 5.5": WL 4738 (reengineering of server variables)
had broken the 5.1 behaviour of --log-error: --log-error without argument sent to stderr instead of writing
to a file with an autogenerated name.

The unit test pfs_instr-t:
- generates a very long (10,000) bytes file name
- calls find_or_create_file.

This leads to a buffer overflow in mysys in my_realpath(),
because my_realpath and mysys file APIs in general do not
test for input parameters: mysys assumes every file name
is less that FN_REFLEN in length.

Calling find_or_create_file with a very long file name is likely
to happen when instrumenting third party code that does not use mysys,
so this test is legitimate.

The fix is to make find_or_create_file in the performance schema
more robust in this case.

The root cause of the failure is that when
Bug#51447 performance schema evil twin files
was fixed, instrumented file names got normalized.

The pfs-t unit test depends on this file normalization,
but it was not updated.

This fix aligns pfs-t.cc lookup_file_by_name()
with the logic in pfs_instr.cc find_or_create_file().

and "README" (header part: "This is a release of MySQL ...")
from "trunk" to "next-mr".

by adding the header part "This is MySQL ...".