[Bug preprocessor/63831] [5 Regression] r217292 causes segfaults with -MM

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63831

--- Comment #15 from Iain Sandoe <iains at gcc dot gnu.org> ---
Reproducer:

$ cat t.h
#ifdef __has_attribute
  #if __has_attribute(availability)
     /* use better attributes if possible */
  #endif
#endif

gcc-trunk-bust$ ./gcc/xgcc -Bgcc t.h -E >t.i
gcc-trunk-bust$ more t.i
# 1 "t.h"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "t.h"
__has_attribute__ (availability)