[libcxx] Include <sys/time.h> in posix_compat.h

[phosek]

Summary

posix_compat.h uses struct timeval which is defined in <sys/time.h>
but it doesn't include it. On most POSIX platforms like Linux or macOS,
that headers is transitively included by other headers like <sys/stat.h>,
but there are other platforms where this is not the case.

[phosek]

We noticed this in our downstream CI after D152377 landed where we started getting build errors like these:

In file included from /b/s/w/ir/x/w/llvm-llvm-project/libcxx/src/filesystem/directory_entry.cpp:16:
/b/s/w/ir/x/w/llvm-llvm-project/libcxx/src/filesystem/time_utils.h:263:16: error: incomplete result type 'TimeVal' (aka 'std::filesystem::detail::(anonymous namespace)::timeval') in function definition
  263 | inline TimeVal make_timeval(TimeSpec const& ts) {
      |                ^

[zibi]

LGTM,

this fixes exact same issue on z/OS. Thank you for a quick fix.

[ldionne]

LGTM post-commit.

libcxx/src/filesystem/posix_compat.h

 # include <windows.h>
 # include <io.h>
 # include <winioctl.h>
 #else
 # include <fcntl.h>
 # include <unistd.h>
 # include <sys/stat.h>
 # include <sys/statvfs.h>
+# include <sys/time.h>
 #endif
 #include <stdlib.h>
 #include <time.h>
 
 #if defined(_LIBCPP_WIN32API)
 // This struct isn't defined in the normal Windows SDK, but only in the
 // Windows Driver Kit.
 struct LIBCPP_REPARSE_DATA_BUFFER {