Don't fail configure if getxattr is not available (SmartOS)

The code is already prepared for the case that it's not available.
9 jobs for getxattr in 16 minutes and 2 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Build
passed #317285
cross-android_api21_arm64

00:03:05

passed #317286
cross-android_api28_arm64

00:03:03

passed #317287
cross-mingw64

00:03:41

passed #317283
debian-stable-x86_64

00:03:59

passed #317282
fedora-x86_64

00:06:23

passed #317284
G_DISABLE_ASSERT

00:03:59

passed #317288
win32
msys2-mingw32

00:14:22

passed #317289
win32
vs2017-x64

00:09:52

 
  Coverage
passed #317290
coverage

00:01:39

78.1%