re PR go/61880 (Linking with external functions in C does not work in GO when…

re PR go/61880 (Linking with external functions in C does not work in GO when using gccgo, while it works in gc)

	PR go/61880
compiler: symbol names should have '.' replaced with '_'

Package and symbol names issued by the cgo tool and compiler
should be the same for the object files to link.

A minimal change to fix only:
   https://code.google.com/p/gofrontend/issues/detail?id=36
and
   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61880

From-SVN: r215810

gcc/go/gofrontend/gogo.cc

@@ -258,10 +258,7 @@ Gogo::pkgpath_for_symbol(const std::string& pkgpath)
       char c = s[i];
       if ((c >= 'a' && c <= 'z')
 	  || (c >= 'A' && c <= 'Z')
-	  || (c >= '0' && c <= '9')
-	  || c == '_'
-	  || c == '.'
-	  || c == '$')
+	  || (c >= '0' && c <= '9'))
 	;
       else
 	s[i] = '_';