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/fileio.c b/src/fileio.c
index 3d6ff0d..9eecb01 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -2501,7 +2501,7 @@
 	check_cursor_lnum();
 	beginline(BL_WHITE | BL_FIX);	    // on first non-blank
 
-	if (!cmdmod.lockmarks)
+	if ((cmdmod.cmod_flags & CMOD_LOCKMARKS) == 0)
 	{
 	    // Set '[ and '] marks to the newly read lines.
 	    curbuf->b_op_start.lnum = from + 1;