y2038: linux: Provide __utimes64 implementation

This patch provides new __utimes64 explicit 64 bit function for setting file's
64 bit attributes for access and modification time.

Internally, the __utimensat64_helper function is used. This patch is necessary
for having architectures with __WORDSIZE == 32 Y2038 safe.

Moreover, a 32 bit version - __utimes has been refactored to internally use
__utimes64.

The __utimes is now supposed to be used on systems still supporting 32
bit time (__TIMESIZE != 64) - hence the necessary conversion of struct
timeval to 64 bit struct __timeval64.

Build tests:
./src/scripts/build-many-glibcs.py glibcs

Run-time tests:
- Run specific tests on ARM/x86 32bit systems (qemu):
  https://github.com/lmajewski/meta-y2038 and run tests:
  https://github.com/lmajewski/y2038-tests/commits/master



Above tests were performed with Y2038 redirection applied as well as without
to test proper usage of both __utimes64 and __utimes.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>