Bug#42733: Type-punning warnings when compiling MySQL -- strict aliasing violations.

Due to the extent of aliasing violations in the MySQL source
code, at this time it is safer to disable strict aliasing related
optimizations in release builds.

As of this patch, only GCC enables strict aliasing by default.
Hence, use the -fno-strict-aliasing option to disable the
aliasing rules.

cmake/build_configurations/mysql_release.cmake

@@ -131,12 +131,12 @@ IF(UNIX)
 
   # Default GCC flags
   IF(CMAKE_COMPILER_IS_GNUCC)
-    SET(COMMON_C_FLAGS               "-g -static-libgcc -fno-omit-frame-pointer")
+    SET(COMMON_C_FLAGS               "-g -static-libgcc -fno-omit-frame-pointer -fno-strict-aliasing")
     SET(CMAKE_C_FLAGS_DEBUG          "-O ${COMMON_C_FLAGS}")
     SET(CMAKE_C_FLAGS_RELWITHDEBINFO "-O3 ${COMMON_C_FLAGS}")
   ENDIF()
   IF(CMAKE_COMPILER_IS_GNUCXX)
-    SET(COMMON_CXX_FLAGS               "-g -static-libgcc -fno-omit-frame-pointer")
+    SET(COMMON_CXX_FLAGS               "-g -static-libgcc -fno-omit-frame-pointer -fno-strict-aliasing")
     SET(CMAKE_CXX_FLAGS_DEBUG          "-O ${COMMON_CXX_FLAGS}")
     SET(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O3 ${COMMON_CXX_FLAGS}")
   ENDIF()
@@ -176,9 +176,9 @@ IF(UNIX)
 
   # OSX flags
   IF(APPLE)
-    SET(COMMON_C_FLAGS                 "-g -fno-common")
+    SET(COMMON_C_FLAGS                 "-g -fno-common -fno-strict-aliasing")
     # XXX: why are we using -felide-constructors on OSX?
-    SET(COMMON_CXX_FLAGS               "-g -fno-common -felide-constructors")
+    SET(COMMON_CXX_FLAGS               "-g -fno-common -felide-constructors -fno-strict-aliasing")
     SET(CMAKE_C_FLAGS_DEBUG            "-O ${COMMON_C_FLAGS}")
     SET(CMAKE_CXX_FLAGS_DEBUG          "-O ${COMMON_CXX_FLAGS}")
     SET(CMAKE_C_FLAGS_RELWITHDEBINFO   "-Os ${COMMON_C_FLAGS}")