patch: fix -p -1 handling
checkstack.pl: add blackfin (by Alex Landau <landau_alex@yahoo.com>)

diff --git a/editors/patch.c b/editors/patch.c
index 5f7f7d0..f071a08 100644
--- a/editors/patch.c
+++ b/editors/patch.c
@@ -55,10 +55,12 @@
 	int i;
 
 	/* Terminate string at end of source filename */
-	temp = strchr(filename_start_ptr, '\t');
-	if (temp) *temp = 0;
+	temp = strchrnul(filename_start_ptr, '\t');
+	*temp = '\0';
 
-	/* skip over (patch_level) number of leading directories */
+	/* Skip over (patch_level) number of leading directories */
+	if (patch_level == -1)
+		patch_level = INT_MAX;
 	for (i = 0; i < patch_level; i++) {
 		temp = strchr(filename_start_ptr, '/');
 		if (!temp)