i386: Inline function with default arch/tune to caller

i386: Inline function with default arch/tune to caller

For function with different target attributes, current logic rejects to
inline the callee when any arch or tune is mismatched. Relax the
condition to allow callee with default arch/tune to be inlined.

gcc/ChangeLog:

	* config/i386/i386.cc (ix86_can_inline_p): If callee has
	default arch=x86-64 and tune=generic, do not block the
	inlining to its caller. Also allow callee with different
	arch= to be inlined if it has always_inline attribute and
	it's ISA is subset of caller's.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/inline_attr_arch.c: New test.
	* gcc.target/i386/inline_target_clones.c: Ditto.