[binutils-gdb] Fix "make test-cp-name-parser"

[sergiodj+buildbot at sergiodj dot net]

*** TEST RESULTS FOR COMMIT 2a1dde5da23779fd0d269c3e51c7814aba9001dd ***

Author: Pedro Alves <palves@redhat.com>
Branch: master
Commit: 2a1dde5da23779fd0d269c3e51c7814aba9001dd

Fix "make test-cp-name-parser"

src/gdb/cp-name-parser.y: In function int main(int, char**):
src/gdb/cp-name-parser.y:2132:30: error: ISO C++ forbids converting a string constant to char* [-Werror=write-strings]
   char *str2, *extra_chars = "", c;
                              ^

Simply don't initialize the variable, it's not necessary.

gdb/ChangeLog:
2017-11-08  Pedro Alves  <palves@redhat.com>

	* cp-name-parser.y (main): Don't initialize extra_chars.