driver-i386.c (describe_cache): Add l2_sizekb argument.

	* config/i386/driver-i386.c (describe_cache): Add l2_sizekb argument.
	Pass L2 size as "--param l2-cache-size" to the compiler.
	(decode_l2_cache): New function to decode L2 cache parameters using
	0x8000006 extended cpuid function.
	(detect_caches_amd): Determine parameters of L2 cache using
	decode_l2_caches function.
	(decode_caches_intel): Decode L2 cache parameters.
	(detect_caches_intel): Determine L2 cache parameters using
	decode_caches_intel and decode_l2_caches functions.

From-SVN: r133890