patch 9.1.1396: 'errorformat' is a global option

Problem:  The 'grepformat' option is global option, but it would be
          useful to have it buffer-local, similar to 'errorformat' and
          other quickfix related options (Dani Dickstein)
Solution: Add the necessary code to support global-local 'grepformat',
          allowing different buffers to parse different grep output
          formats (glepnir)

fixes: #17316
closes: #17315

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/structs.h b/src/structs.h
index cd7370d..00b0746 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -3371,6 +3371,7 @@
      * local values for options which are normally global
      */
 #ifdef FEAT_QUICKFIX
+    char_u	*b_p_gefm;	// 'grepformat' local value
     char_u	*b_p_gp;	// 'grepprg' local value
     char_u	*b_p_mp;	// 'makeprg' local value
     char_u	*b_p_efm;	// 'errorformat' local value