checkpatch: add control statement test to SINGLE_STATEMENT_DO_WHILE_MACRO

Commit b13edf7f ("checkpatch: add checks for do {} while (0) macro
misuses") added a test that is overly simplistic for single statement
macros.

Macros that start with control tests should be enclosed in a do {} while
(0) loop.

Add the necessary control tests to the check.
Signed-off-by: NJoe Perches <joe@perches.com>
Acked-by: NAndy Whitcroft <apw@canonical.com>
Tested-by: NFranz Schrober <franzschrober@yahoo.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -3016,7 +3016,8 @@ sub process {
 					$herectx .= raw_line($linenr, $n) . "\n";
 				}
 
-				if (($stmts =~ tr/;/;/) == 1) {
+				if (($stmts =~ tr/;/;/) == 1 &&
+				    $stmts !~ /^\s*(if|while|for|switch)\b/) {
 					WARN("SINGLE_STATEMENT_DO_WHILE_MACRO",
 					     "Single statement macros should not use a do {} while (0) loop\n" . "$herectx");
 				}