[sanitizer] Symbolic ioctl names.

Replace hardcoded ioctl request ids with symbolic names.
Disable certain ioctls on platforms where such names are not found in the
system headers.
Fix a bug in ioctl_lookup.
Reenable ioctl test on Mac.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@184183 91177308-0d34-0410-b5e6-96231b3b80d8
[sanitizer] Replace ext2_ ioctls with generic fs_ ioctls.

They are actually the same, but ext2_fs.h header is not available in userspace
with newer kernels.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@184184 91177308-0d34-0410-b5e6-96231b3b80d8