[Bug c++/58057] gcc lexer cannot parse extern "\x43" void blah() with option -std=c++0x;

[3dw4rd at verizon dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58057

--- Comment #9 from Ed Smith-Rowland <3dw4rd at verizon dot net> ---
I think I need to test for keyword in addition to testing for macro in
libcpp/lex.c

I'll look at this.

I'll also look at getting a better error.