- API files update.
- Fixed options --cross-call-{unicode-ascii,win32-win16}.
- Minor reorganization of the global checks.

diff --git a/tools/winapi_check/winapi_function.pm b/tools/winapi_check/winapi_function.pm
index 4564d43..fe0c45d 100644
--- a/tools/winapi_check/winapi_function.pm
+++ b/tools/winapi_check/winapi_function.pm
@@ -140,6 +140,10 @@
 	return undef;
     }
 
+    if(!defined($file)) {
+	return undef;
+    }
+
     my @modules;
     foreach my $module (split(/\s*&\s*/, $module)) {
 	if($modules->is_allowed_module_in_file($module, "$current_dir/$file")) {