Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Follow-up to r358851 (llvm-project 10.0.0-rc3 import), where I added
subdirectories for compiler-rt's internal fuzzer, profile and xray
headers, but forgot to add installing those headers themselves.

MFC after: 3 days

Update build glue for libclang_rt.

Update libclang_rt:
* Add cfi, dd, fuzzer and xray
* Update arch support
* Update OptionalObsoleteFiles.inc