MIPS: Default to --with-llsc for the R5900 Linux target as well

MIPS: Default to --with-llsc for the R5900 Linux target as well

The Linux kernel requires and emulates LL and SC for the R5900 too.  The
special --without-llsc default for the R5900 is therefore not applicable
in that case.

Reviewed-by: Maciej W. Rozycki <macro@linux-mips.org>
2018-11-12  Fredrik Noring  <noring@nocrew.org>

	gcc/
	* config.gcc: Update with-llsc defaults for MIPS r5900.

From-SVN: r266038