Make it possible to compile without SAFEMALLOC in debug builds

Default to no SAFEMALLOC on Windows, because C runtime malloc
has this functionslity already

dbug/CMakeLists.txt

@@ -17,6 +17,17 @@ INCLUDE_DIRECTORIES(
   ${CMAKE_SOURCE_DIR}/dbug
   ${CMAKE_SOURCE_DIR}/include 
 )
+IF(WIN32)
+ SET(DEFAULT_SAFEMALLOC OFF)
+ELSE()
+ SET(DEFAULT_SAFEMALLOC ON)
+ENDIF()
+OPTION(WITH_SAFEMALLOC ${DEFAULT_SAFEMALLOC} "Use safemalloc for debug builds. Will result in slower execution.")
+
+IF(WITH_SAFEMALLOC)
+ ADD_DEFINITIONS( -DSAFEMALLOC)
+ENDIF()
+
 SET(DBUG_SOURCES dbug.c)
 ADD_CONVENIENCE_LIBRARY(dbug ${DBUG_SOURCES})
 TARGET_LINK_LIBRARIES(dbug mysys)

dbug/dbug.c

@@ -2253,6 +2253,9 @@ static void free_memory(void *ptr);
 
 void *_db_malloc_(size_t size)
 {
+#ifndef SAFEMALLOC
+  return malloc(size);
+#else
   CODE_STATE *cs= code_state();
   struct st_irem *irem;
   uchar *data;
@@ -2318,10 +2321,14 @@ void *_db_malloc_(size_t size)
 
   TRASH_ALLOC(data, size);
   return data;
+#endif
 }
 
 void *_db_realloc_(void *ptr, size_t size)
 {
+#ifndef SAFEMALLOC
+  return realloc(ptr, size);
+#else
   char *data;
 
   if (!ptr)
@@ -2338,15 +2345,19 @@ void *_db_realloc_(void *ptr, size_t size)
     free_memory(ptr);
   }
   return data;
+#endif
 }
 
 void _db_free_(void *ptr)
 {
+#ifndef SAFEMALLOC
+  free(ptr);
+#else
   if (!ptr || bad_ptr("Freeing", ptr))
     return;
 
    free_memory(ptr);
-  return;
+#endif
 }
 
 static void free_memory(void *ptr)