Remove POSIX clock_gettime() from the common libc time implementation,
since POSIX should not be a dependency for ISO C.
Instead, use the newly added lib/os sys_clock API.
Specifically, sys_clock_gettime().
Signed-off-by: Chris Friedt <cfriedt@tenstorrent.com>
Introduce a place to share implementations of libc functions that
are needed by different libc versions. Place time() in this common
location so it can be shared when building for either minimal libc or
armclang libc.
Signed-off-by: Kumar Gala <kumar.gala@intel.com>