Bug#52514: mysql 5.1 do_abi_check does not compile w/ gcc4.5

           due to GCC preprocessor change
      
The problem is that newer GCC versions treats missing headers
as fatal errors. The solution is to use a guard macro to prevent
the inclusion of system headers when checking the ABI with the
C Preprocessor.

Reference: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15638
           http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44836

Makefile.am:
  Define guard macro.
configure.in:
  Remove workaround.
include/mysql.h:
  Guard the header inclusion.
include/mysql.h.pp:
  Header is not included anymore.

Makefile.am

@@ -314,7 +314,7 @@ abi_check_all:	$(TEST_PREPROCESSOR_HEADER)
 do_abi_check:
 	set -ex; \
 	for file in $(abi_headers); do \
-	         @CC@ -E -nostdinc -dI \
+	         @CC@ -E -nostdinc -dI -DMYSQL_ABI_CHECK \
 	                  -I$(top_srcdir)/include \
 	                  -I$(top_srcdir)/include/mysql \
 	                  -I$(top_srcdir)/sql \

configure.in

@@ -444,16 +444,7 @@ if test "$GCC" != "yes" || expr "$CC" : ".*icc.*"
 then
   ABI_CHECK=""
 else
-  # Workaround GCC >= 4.5 - See Bug#52514
-  case `$CC -dumpversion` in
-    [[4-9]].[[5-9]]*)
-      AC_MSG_WARN([ABI check disabled (GCC >= 4.5)])
-      ABI_CHECK=""
-      ;;
-    *)
-      ABI_CHECK="abi_check"
-      ;;
-  esac
+  ABI_CHECK="abi_check"
 fi
 
 AC_SUBST(ABI_CHECK)

include/mysql.h

@@ -44,7 +44,9 @@ extern "C" {
 #endif
 
 #ifndef _global_h				/* If not standard header */
+#ifndef MYSQL_ABI_CHECK
 #include <sys/types.h>
+#endif
 #ifdef __LCC__
 #include <winsock2.h>				/* For windows */
 #endif

include/mysql.h.pp

-#include <sys/types.h>
 typedef char my_bool;
 typedef int my_socket;
 #include "mysql_version.h"