headers_check: fix perl warnings

According to PBP; best way practice is to use local reference for file
handle and three argument open. Also perl prototypes are a mistake.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: WANG Cong <amwang@redhat.com>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/headers_check.pl

@@ -28,11 +28,12 @@ my $lineno = 0;
 my $filename;
 
 foreach my $file (@files) {
-	local *FH;
 	$filename = $file;
-	open(FH, "<$filename") or die "$filename: $!\n";
+
+	open(my $fh, '<', $filename)
+		or die "$filename: $!\n";
 	$lineno = 0;
-	while ($line = <FH>) {
+	while ($line = <$fh>) {
 		$lineno++;
 		&check_include();
 		&check_asm_types();
@@ -40,7 +41,7 @@ foreach my $file (@files) {
 		&check_declarations();
 		# Dropped for now. Too much noise &check_config();
 	}
-	close FH;
+	close $fh;
 }
 exit $ret;
 
@@ -78,7 +79,7 @@ sub check_config
 }
 
 my $linux_asm_types;
-sub check_asm_types()
+sub check_asm_types
 {
 	if ($filename =~ /types.h|int-l64.h|int-ll64.h/o) {
 		return;