re PR target/70296 (Incorrect handling of vector X; if X is function-like macro)
PR target/70296
* include/cpplib.h (cpp_fun_like_macro_p): New prototype.
* macro.c (cpp_fun_like_macro_p): New function.
* config/rs6000/rs6000-c.c (rs6000_macro_to_expand): If IDENT is
function-like macro, peek following token(s) if it is followed
by CPP_OPEN_PAREN token with optional padding in between, and
if not, don't treat it like a macro.