No 'unsigned vs. 0' warnings in system headers

[Chip Salzenberg]

According to Jeffrey A Law:
>   > 	* c-common.c (shorten_compare): Quiet warnings about unsigned
>   > 	comparisons with zero when they occur in a system header.
> Thanks.  Installed.  Sorry about the delay.

No problem ... but strangely enough, the warnings are _back_ ... even
with this patch, bootstrapping with libstdc++-v3 causes warnings about
unsigned comparisons.  Something about inlining, I bet.
-- 
Chip Salzenberg              - a.k.a. -              <chip@valinux.com>
"I wanted to play hopscotch with the impenetrable mystery of existence,
    but he stepped in a wormhole and had to go in early."  // MST3K