Add linux/userfaultfd.h header file to host glibc am: 9993489d1c am: e49b4b3477 am: 007101a451 am: c2f3c6976a

Original change: https://android-review.googlesource.com/c/platform/prebuilts/gcc/linux-x86/host/x86_64-linux-glibc2.17-4.8/+/1999534

Change-Id: If0081b37839684a5794e0d95723c12acb812404d