[Bug c/96907] New: [docs] document builtins for fputc and putc

[ndesaulniers at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96907

            Bug ID: 96907
           Summary: [docs] document builtins for fputc and putc
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ndesaulniers at google dot com
                CC: rv at rasmusvillemoes dot dk, segher at kernel dot crashing.org
  Target Milestone: ---

In https://reviews.llvm.org/D86508, I'm going through and working on improving
Clang's compatibility with GCC in terms of supported compiler __builtin_
functions.  I noticed that __has_builtin works with putc, __builtin_putc,
fputc, and __builtin_fputc in GCC.  I think putc and fputc could be added to
this page. https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html