Here is another pack of changes about gathering common client code in
sql-common/client.c.
Now i symlink the client.c from sql/ and libmysql/. These directories
have client_settings.h files to be included to client.c. It contains
defines and declarations to compile client.c in appropriate manner.
Also i've added include/sql_common.h, containing declarations of what
is exported from client.c

I removed as many #ifdef-s from client.c as i dared to. I think it's better
push it with some extra #ifdef-s now (of course, if everythihg besides it is
ok) so other people can check the code.


Makefile.am:
  symlinking of sql-common/client.c was added
include/mysql.h:
  MYSQL_CLIENT define moved here from libmysql/Makefile
libmysql/Makefile.am:
  ../libmysql/client_settings.h added to the list of necessary h-files
libmysql/Makefile.shared:
  client.lo added to the list of objects
libmysql/libmysql.c:
  a lot of changes about separating code between libmysql.c and client.c
mysys/default.c:
  changed to keep compiler happy
sql-common/client.c:
  a lot of changes about code separating
sql/Makefile.am:
  mini_client.h has to be removed
sql/repl_failsafe.cc:
  mysql_real_connect prototype was unified, so we've got to set connection timeout separately
sql/slave.cc:
  trimming code to the changed function's prototypes
sql/sql_repl.cc:
  mini_client isn't needed anymore