(parse_escape): Support \E and \e like cc1:

they mean \033, and they generate a warning if pedantic.

From-SVN: r3410

gcc/cexp.y

@@ -748,6 +748,9 @@ parse_escape (string_ptr)
     case 'b':
       return TARGET_BS;
     case 'e':
+    case 'E':
+      if (pedantic)
+	pedwarn ("non-ANSI-standard escape sequence, `\\%c'", c);
       return 033;
     case 'f':
       return TARGET_FF;