Implemented an internal getrandom to avoid calls to the public one in
table.h

---------

Co-authored-by: Sriya Pratipati <sriyap@google.com>

The previous internal fcntl implementation modified errno directly, this
patch fixes that. This patch also moves open and close into OSUtil since
they are used in multiple places. There are more places that need
similar cleanup but only got comments in this patch to keep it
relatively reviewable.

Related to: https://github.com/llvm/llvm-project/issues/143937

Since errno was moved in
https://github.com/llvm/llvm-project/pull/143187 the code including it
in https://github.com/llvm/llvm-project/pull/141393 was rendered
incorrect. This patch fixes the include and the cmake depends.

Closes #85275
Closes #90317
Updates #97191

---------

Co-authored-by: Joseph Huber <huberjn@outlook.com>
Co-authored-by: Michael Jones <michaelrj@google.com>

This is the first step in preparation for:
https://discourse.llvm.org/t/rfc-make-clang-builtin-math-functions-constexpr-with-llvm-libc-to-support-c-23-constexpr-math-functions/86450

These functions don't have a _time64 variant, so we can't use time_t
directly (since our time_t is a uint64_t). The workaround is to use
longs when doing the syscall and write back when necessary.

RV32 uses SYS_utimensat_time64 instead of SYS_utimensat but the call is
the same.

We define SYS_fchmodat2 on libc but the syscall is not available on old
kernels, so prefer the SYS_fchmodat version when possible.

#133983

Simple cleanup