Core/Misc: Add PERFORMANCE_PROFILING CMake option

Add a new CMake option called PERFORMANCE_PROFILING that should be used only when profiling the performance.
This option is unsupported, do not report any issue happening when enabling this option.

cmake/showoptions.cmake

@@ -105,6 +105,13 @@ if ( HELGRIND )
   add_definitions(-DHELGRIND)
 endif()
 
+if ( PERFORMANCE_PROFILING )
+  message("")
+  message(" *** PERFORMANCE_PROFILING - WARNING!")
+  message(" *** Please note that this is for PERFORMANCE PROFILING only! Do NOT report any issue when enabling this configuration!")
+  add_definitions(-DPERFORMANCE_PROFILING)
+endif()
+
 if (BUILD_SHARED_LIBS)
   message("")
   message(" *** WITH_DYNAMIC_LINKING - INFO!")