Remove unused autoconf check: gettimeofday(3)

Remove unused autoconf check: gettimeofday(3)

The macro HAVE_GETTIMEOFDAY is not being used anywhere.

BTW, the function is defined by SVr4, 4.3BSD, and POSIX.1-2001, so
it's likely that it is always available.

POSIX.1-2008 marks it as obsolete, but only because
clock_gettime(2) provides more precission.  Since gettimeofday(3)
is in use by many big projects, and it has no obvious dangers,
it's likely that it will continue to exist even if it's outside of
the POSIX standard.

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>