[ARM] Improve max_cond_insns setting for Cortex cores

[ARM] Improve max_cond_insns setting for Cortex cores

To enable cores to use the correct max_cond_insns setting, use the core-specific
tuning when a CPU/tune is selected unless -mrestrict-it is explicitly set.

On Cortex-A57 this gives 1.1% performance gain on SPECINT2006 as well as a
0.4% codesize reduction.

    gcc/
	* config/arm/arm.c (arm_option_override_internal):
	Use max_cond_insns from CPU tuning unless -mrestrict-it is used.

From-SVN: r278968