patch 8.2.3292: underscore in very magic pattern causes a hang

Problem:    Underscore in very magic pattern causes a hang.  Pattern with \V
            are case sensitive. (Yutao Yuan)
Solution:   Adjust condition for magicness and advance pointer. (Christian
            Brabandt, closes #8707, closes #8704, closes #8705)
diff --git a/src/search.c b/src/search.c
index 4396651..3b6b437 100644
--- a/src/search.c
+++ b/src/search.c
@@ -445,7 +445,7 @@
 		return TRUE;
 	    p += l;
 	}
-	else if (*p == '\\' && magic_val == MAGIC_ON)
+	else if (*p == '\\' && magic_val <= MAGIC_ON)
 	{
 	    if (p[1] == '_' && p[2] != NUL)  // skip "\_X"
 		p += 3;
@@ -460,6 +460,8 @@
 	{
 	    if (p[1] != NUL)  // skip "_X" and %X
 		p += 2;
+	    else
+		p++;
 	}
 	else if (MB_ISUPPER(*p))
 	    return TRUE;