tools: Check for open return code in Perl scripts.
diff --git a/tools/winapi/winapi_fixup b/tools/winapi/winapi_fixup
index 2354723..334aa52 100755
--- a/tools/winapi/winapi_fixup
+++ b/tools/winapi/winapi_fixup
@@ -61,7 +61,7 @@
     $output->prefix("$file:");
 
     {
-	open(IN, "< $file");
+	open(IN, "< $file") || die "Error: Can't open $file: $!\n";
 	local $/ = undef;
 	$_ = <IN>;
 	close(IN);