utimes: Export utimensat based utimes

utimes: Export utimensat based utimes

sys/time.h has libc_hidden_proto(utimes) which generates the hidden
"__GI_utimes" symbol reference, and common/utimes.c has a
libc_hidden_def(utimes) which generates the exported "utimes" alias.

As part of no-legacy-syscall kernel ABI, Commit 80dc2ed05
"utimes: Use utimensat if arch does not have the utimes syscall"
introduced a new wrapper, but missed the corresponding libc_hidden_def,
causing Busybox (1.20.0) link to fail (for ARC).

Also don't generate a STUB, in that case.
---------------->8-------------------
....
touch.c:(.text.touch_main+0xdc): undefined reference to `utimes'
touch.c:(.text.touch_main+0x114): undefined reference to `utimes'
libbb/lib.a(copy_file.o): In function `copy_file':
copy_file.c:(.text.copy_file+0x446): undefined reference to `utimes'
collect2: ld returned 1 exit status
---------------->8-------------------

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>