Fix signedness warning in glib/tests/fileutils.c

glib/gtestutils.h:134:96: error: comparison of integer expressions of different signedness: ‘gint’ {aka ‘int’} and ‘GFileError’
  134 |                                                if (!err || (err)->domain != dom || (err)->code != c) \
      |                                                                                                ^~
glib/tests/fileutils.c:1072:15: note: in expansion of macro ‘g_assert_error’
 1072 |               g_assert_error (error, G_FILE_ERROR, tests[i].expected_error);
      |               ^~~~~~~~~~~~~~
10 jobs for fix_warnings in 20 minutes and 45 seconds (queued for 3 minutes and 11 seconds)
Status Job ID Name Coverage
  Style Check
passed #911676
check-todos

00:02:41

failed #911675
allowed to fail
style-check-diff

00:02:37

 
  Build
passed #911679
cross-android_api21_arm64

00:01:46

passed #911680
cross-android_api28_arm64

00:03:07

passed #911681
cross-mingw64

00:02:32

passed #911678
debian-stable-x86_64

00:03:22

passed #911677
fedora-x86_64

00:10:35

passed #911682
win32-ps
msys2-mingw32

00:07:24

passed #911683
win32-ps
vs2017-x64

00:08:03

 
  Coverage
passed #911684
coverage

00:01:16

78.4%
 
Name Stage Failure
failed
style-check-diff Style Check
+check_utf8_to_utf16 (const char *utf8,
+ gsize utf8_len,
+ const gunichar2 *utf16,
+ glong utf16_len,
+ glong error_pos)
{
gunichar2 *result, *result2, *result3;
glong items_read, items_read2;
ERROR: Job failed: exit code 1