patch 8.2.4750: small pieces of dead code

Problem:    Small pieces of dead code.
Solution:   Remove the dead code. (Goc Dundar, closes #10190) Rename the
            qftf_cb struct member to avoid confusion.
diff --git a/src/misc1.c b/src/misc1.c
index 6dbad3f..af83c10 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -1576,7 +1576,7 @@
 		c = (int)STRLEN(var);
 		// if var[] ends in a path separator and tail[] starts
 		// with it, skip a character
-		if (*var != NUL && after_pathsep(dst, dst + c)
+		if (after_pathsep(dst, dst + c)
 #if defined(BACKSLASH_IN_FILENAME) || defined(AMIGA)
 			&& dst[-1] != ':'
 #endif