Use a guard macro to prevent the inclusion of system headers

when checking the ABI with the C Preprocessor. Also, add the
new hearders to the cmake based ABI check.

cmake/abi_check.cmake:
  Add headers which were added to the autotools ABI check.
  Remove trailing spaces.
include/mysql/client_plugin.h:
  Guard the inclusion of system headers.

Makefile.am

@@ -263,6 +263,8 @@ test-full-qa:
 #
 # Headers which need to be checked for abi/api compatibility.
 #
+# Attention: do not forget to also add to cmake/abi_check.cmake
+#
 
 API_PREPROCESSOR_HEADER = $(top_srcdir)/include/mysql/plugin_audit.h \
 			$(top_srcdir)/include/mysql/plugin_ftparser.h \

cmake/abi_check.cmake

@@ -33,6 +33,8 @@ IF(CMAKE_COMPILER_IS_GNUCC AND CMAKE_SYSTEM_NAME MATCHES "Linux")
     ${CMAKE_SOURCE_DIR}/include/mysql.h
     ${CMAKE_SOURCE_DIR}/include/mysql/psi/psi_abi_v1.h
     ${CMAKE_SOURCE_DIR}/include/mysql/psi/psi_abi_v2.h
+    ${CMAKE_SOURCE_DIR}/include/mysql/client_plugin.h
+    ${CMAKE_SOURCE_DIR}/include/mysql/plugin_auth.h
   )
 
   ADD_CUSTOM_TARGET(abi_check ALL

include/mysql/client_plugin.h

@@ -23,8 +23,10 @@
 */
 #define MYSQL_CLIENT_PLUGIN_INCLUDED
 
+#ifndef MYSQL_ABI_CHECK
 #include <stdarg.h>
 #include <stdlib.h>
+#endif
 
 /* known plugin types */
 #define MYSQL_CLIENT_reserved1               0

include/mysql/client_plugin.h.pp

-#include <stdarg.h>
-#include <stdlib.h>
 struct st_mysql_client_plugin
 {
   int type; unsigned int interface_version; const char *name; const char *author; const char *desc; unsigned int version[3]; const char *license; void *mysql_api; int (*init)(char *, size_t, int, va_list); int (*deinit)(); int (*options)(const char *option, const void *);