[PCH bug] anonymous variadic macros were introduced in C99 warning at pch using

[Vladimir Merzliakov]

simple test.c test.h files compile without using pch
and generate strange warning if use test.h.gch

All case with options: g++ -ansi -pedantic -Werror -Winvalid-pch

-test.h----8<-----------
#include<string>
-test.h---->8-----------

-test.cc---8<-----------
#include"test.h"

int main() {
  return 0;
}
-test.cc--->8-----------

Warning generated at line in concept_check.h:52 :

#define __glibcpp_function_requires(...)

Vladimir