Bug#29125 Windows Server X64: so many compiler warnings

- Remove bothersome warning messages.  This change focuses on the warnings 
that are covered by the ignore file: support-files/compiler_warnings.supp.
- Strings are guaranteed to be max uint in length

mysys/safemalloc.c

@@ -174,7 +174,7 @@ void *_mymalloc(size_t size, const char *filename, uint lineno, myf MyFlags)
   data[size + 3]= MAGICEND3;
   irem->filename= (char *) filename;
   irem->linenum= lineno;
-  irem->datasize= size;
+  irem->datasize= (uint32) size;
   irem->prev=	  NULL;
 
   /* Add this remember structure to the linked list */