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

server-tools/instance-manager/buffer.cc

@@ -100,7 +100,7 @@ err:
 
 int Buffer::get_size()
 {
-  return buffer_size;
+  return (uint) buffer_size;
 }