Fix internal error during inlining after ICF pass

The problem is that the ICF pass identifies two functions, one of which has
a static chain while the other does not.  The fix is simply to prevent this
identification from occurring.

gcc/
	PR ipa/113996
	* ipa-icf.cc (sem_function::get_hash): Hash DECL_STATIC_CHAIN.
	(sem_function::equals_wpa): Compare it.
	(sem_function::equals_private): Likewise.

gcc/testsuite/
	* gnat.dg/lto27.adb: New test.