gcc for glibc 2.3

[Roland McGrath]

I moved __uselocale to GLIBC_2.3; all the __ names for the new locale fns have
always been prototyped.  Are you saying we should remove those prototypes
from the installed headers?  I suppose if libstdc++ uses decls like
extern __typeof (uselocale) __uselocale; is won't be error prone not
to have them.  Still, I am dubious about removing the prototypes.

strftime_l and wcsftime_l do not exist at all.  I can write them real quick.