Summary: Some syscalls like SYS_clone do not tolerate a return instruction after the syscall instruction. Marking the syscall functions with the `always_inline` attribute accommodates such syscalls as inlining eliminates the return instruction. Reviewers: abrachet, phosek Subscribers: MaskRay, tschuett, libc-commits Tags: #libc-project Differential Revision: https://reviews.llvm.org/D72102