Adds $glob_basedir/sbin to search path when needed

Added $glob_basedir/sbin to search path for relevant binaries

                  
The problem here is that embedded server starts handle_thread manager 
thread  on mysql_library_init() does not stop it on mysql_library_end().
At shutdown, my_thread_global_end() waits for thread count to become 0,
but since we did not stop the thread it will give up after 5 seconds.
             
Solution is to move shutdown for handle_manager thread from kill_server()
(mysqld specific) to clean_up() that is used by both embedded and mysqld.
            
This patch also contains some refactorings - to avoid duplicate code,
start_handle_manager() and stop_handle_manager() functions are introduced.
Unused variables are eliminated. handle_manager does not rely on global
variable abort_loop anymore to stop (abort_loop is not set for embedded).
            
Note: Specifically on Windows and when using DBUG version of libmysqld, 
the complete solution requires removing obsolete code my_thread_init() 
from my_thread_var(). This has a side effect that a DBUG statement 
after my_thread_end() can cause thread counter to be incremented, and 
embedded will hang for some seconds. Or worse, my_thread_init() will 
crash if critical sections have been deleted by the global cleanup 
routine that runs in a different thread. 

This patch also fixes and revert prior changes for Bug#38293 
"Libmysqld crash in mysql_library_init if language file missing".

Root cause of the crash observed in Bug#38293  was bug in my_thread_init() 
described above

There was a missing initialization.

with non-RSA-requesting client if server uses RSA key

matchSuite() may not find a match. 
It will return error in this case.
Added a error checking code that will prevent using uninitialized 
memory in the code based on the assumption 
that matchSuite() has found a match.

                  
Updated MySQL time handling code to react correctly on UTC leap second additions.
MySQL functions that return the OS current time, like e.g. CURDATE(), NOW() etc
will return :59:59 instead of :59:60 or 59:61.
As a result the reader will receive :59:59 for 2 or 3 consecutive seconds 
during the leap second.
This fix will not affect the values returned by UNIX_TIMESTAMP() for leap seconds.
But note that when converting the value returned by UNIX_TIMESTAMP() to broken 
down time the correction of leap seconds will still be applied.
Note that this fix will make a difference *only* if the OS is specially configured
to return leap seconds from the OS time calls or when using a MySQL time zone 
defintion that has leap seconds.
Even after this change date/time literals (or other broken down time 
representations) with leap seconds (ending on :59:60 or 59:61) will still be 
considered illegal and discarded by the server with an error or 
a warning depending on the sql mode.
Added a test case to demonstrate the effect of the fix.

by using and taking out a full path.

TABLE_LIST doesn't free Strings in its string lists
(TABLE_LIST::use_index and TABLE_liST::ignore_index), so
calling c_ptr_safe() on that Strings leads to memleaks.
OTOH "safe" c_ptr_safe() is not necessary there and we can
replace it with c_ptr().

Diff to actual 5.0-bugteam is revno: 2725 only

            leads to an assertion failure

Any run-time error in stored function (like recursive function
call or update of table that is already updating by statement
which invoked this stored function etc.) that was used in some
expression of the single-table UPDATE statement caused an
assertion failure.
Multiple-table UPDATE (as well as INSERT and both single- and
multiple-table DELETE) are not affected.

            an error

Even after the fix for bug 28701 visible behaviors of
SELECT FROM a view and SELECT FROM a regular table are
little bit different:

1. "SELECT FROM regular table USE/FORCE/IGNORE(non
   existent index)" fails with a "ERROR 1176 (HY000):
   Key '...' doesn't exist in table '...'"

2. "SELECT FROM view USING/FORCE/IGNORE(any index)" fails
   with a "ERROR 1221 (HY000): Incorrect usage of
   USE/IGNORE INDEX and VIEW".  OTOH "SHOW INDEX FROM
   view" always returns empty result set, so from the point
   of same behaviour view we trying to use/ignore non
   existent index.

To harmonize the behaviour of USE/FORCE/IGNORE(index)
clauses in SELECT from a view and from a regular table the
"ERROR 1221 (HY000): Incorrect usage of USE/IGNORE INDEX
and VIEW" message has been replaced with the "ERROR 1176
(HY000): Key '...' doesn't exist in table '...'" message
like for tables and non existent keys.

      
The SHOW VARIABLES LIKE .../SELECT @@/SELECT ... FROM INFORMATION_SCHEMA.VARIABLES
were assuming that all the system variables are in system charset (UTF-8).
However the variables that are settable through command line will have a different
character set (character_set_filesystem).
Fixed the server to remember the correct character set of basedir, datadir, tmpdir,
ssl, plugin_dir, slave_load_tmpdir, innodb variables; init_connect and init_slave 
variables and use it when processing data.