[llvm-rc] Allow -1 for menu item IDs
This seems to be used in some resource files, e.g.
MSVC rc.exe and GNU windres both allow any value here, and silently
just truncate to uint16_t range. This just explicitly allows the
-1 value and errors out on others - the same was done for control
IDs in dialogs in c1a67857ba0a6ba558818b589fe7c0fcc8f238ae.
Differential Revision: https://reviews.llvm.org/D76951