patch 8.1.0552: saved last search pattern may not be restored

Problem:    Saved last search pattern may not be restored.
Solution:   Call restore_last_search_pattern().  Add a check for balancing
            saving and restoring the last search pattern.
diff --git a/src/ex_getln.c b/src/ex_getln.c
index acccd27..bfda942 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -462,6 +462,7 @@
     int		use_last_pat;
 
     // Parsing range may already set the last search pattern.
+    // NOTE: must call restore_last_search_pattern() before returning!
     save_last_search_pattern();
 
     if (!do_incsearch_highlighting(firstc, is_state, &skiplen, &patlen))
@@ -633,6 +634,7 @@
     int	    save;
 
     // Parsing range may already set the last search pattern.
+    // NOTE: must call restore_last_search_pattern() before returning!
     save_last_search_pattern();
 
     if (!do_incsearch_highlighting(firstc, is_state, &skiplen, &patlen))
@@ -735,6 +737,7 @@
     int		skiplen, patlen;
 
     // Parsing range may already set the last search pattern.
+    // NOTE: must call restore_last_search_pattern() before returning!
     save_last_search_pattern();
 
     if (!do_incsearch_highlighting(firstc, is_state, &skiplen, &patlen))
@@ -742,6 +745,7 @@
 	restore_last_search_pattern();
 	return FAIL;
     }
+    restore_last_search_pattern();
 
     // Add a character from under the cursor for 'incsearch'.
     if (is_state->did_incsearch)