checkpatch: add --fix option for ASSIGN_IN_IF

Add a --fix option for 2 types of single-line assignment in if statements

	if ((foo = bar(...)) < BAZ) {
expands to:
	foo = bar(..);
	if (foo < BAZ) {
and
	if ((foo = bar(...)) {
expands to:
	foo = bar(...);
	if (foo) {

if statements with assignments spanning multiple lines are
not converted with the --fix option.

if statements with additional logic are also not converted.

e.g.:	if ((foo = bar(...)) & BAZ == BAZ) {
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Link: http://lkml.kernel.org/r/9bc7c782516f37948f202deba511bc95ed279bbd.camel@perches.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -5020,8 +5020,30 @@ sub process {
 			my ($s, $c) = ($stat, $cond);
 
 			if ($c =~ /\bif\s*\(.*[^<>!=]=[^=].*/s) {
-				ERROR("ASSIGN_IN_IF",
-				      "do not use assignment in if condition\n" . $herecurr);
+				if (ERROR("ASSIGN_IN_IF",
+					  "do not use assignment in if condition\n" . $herecurr) &&
+				    $fix && $perl_version_ok) {
+					if ($rawline =~ /^\+(\s+)if\s*\(\s*(\!)?\s*\(\s*(($Lval)\s*=\s*$LvalOrFunc)\s*\)\s*(?:($Compare)\s*($FuncArg))?\s*\)\s*(\{)?\s*$/) {
+						my $space = $1;
+						my $not = $2;
+						my $statement = $3;
+						my $assigned = $4;
+						my $test = $8;
+						my $against = $9;
+						my $brace = $15;
+						fix_delete_line($fixlinenr, $rawline);
+						fix_insert_line($fixlinenr, "$space$statement;");
+						my $newline = "${space}if (";
+						$newline .= '!' if defined($not);
+						$newline .= '(' if (defined $not && defined($test) && defined($against));
+						$newline .= "$assigned";
+						$newline .= " $test $against" if (defined($test) && defined($against));
+						$newline .= ')' if (defined $not && defined($test) && defined($against));
+						$newline .= ')';
+						$newline .= " {" if (defined($brace));
+						fix_insert_line($fixlinenr + 1, $newline);
+					}
+				}
 			}
 
 			# Find out what is on the end of the line after the