[sanitizer] fix linux_dirent for SANITIZER_X32; based on patch by H.J. Lu

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@209281 91177308-0d34-0410-b5e6-96231b3b80d8
[asan] Fix x86 asm instrumentation to preserve flags.

This change also enables asm instrumentation in asan tests that was
accidentally disabled yearlier, and adds a sanity test for that.

Patch by Yuri Gorshenin.



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@209282 91177308-0d34-0410-b5e6-96231b3b80d8