checkpatch: improve the unnecessary OOM message test

Use the context around a patch to avoid missing some candidates.

Link: http://lkml.kernel.org/r/865e874fbae5decc331a849bd8d71c325db6bc80.1496343345.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -5311,7 +5311,7 @@ sub process {
 			my ($s, $c) = ctx_statement_block($linenr - 3, $realcnt, 0);
 #			print("line: <$line>\nprevline: <$prevline>\ns: <$s>\nc: <$c>\n\n\n");
 
-			if ($c =~ /(?:^|\n)[ \+]\s*(?:$Type\s*)?\Q$testval\E\s*=\s*(?:\([^\)]*\)\s*)?\s*(?:devm_)?(?:[kv][czm]alloc(?:_node|_array)?\b|kstrdup|(?:dev_)?alloc_skb)/) {
+			if ($s =~ /(?:^|\n)[ \+]\s*(?:$Type\s*)?\Q$testval\E\s*=\s*(?:\([^\)]*\)\s*)?\s*(?:devm_)?(?:[kv][czm]alloc(?:_node|_array)?\b|kstrdup|kmemdup|(?:dev_)?alloc_skb)/) {
 				WARN("OOM_MESSAGE",
 				     "Possible unnecessary 'out of memory' message\n" . $hereprev);
 			}