patch 8.2.1898: command modifier parsing always uses global cmdmod

Problem:    Command modifier parsing always uses global cmdmod.
Solution:   Pass in cmdmod_T to use.  Rename struct fields consistently.
diff --git a/src/scriptfile.c b/src/scriptfile.c
index 4f3e94e..6f44764 100644
--- a/src/scriptfile.c
+++ b/src/scriptfile.c
@@ -979,7 +979,7 @@
 ex_source(exarg_T *eap)
 {
 #ifdef FEAT_BROWSE
-    if (cmdmod.browse)
+    if (cmdmod.cmod_flags & CMOD_BROWSE)
     {
 	char_u *fname = NULL;