lower-bitint: Handle uninitialized large/huge SSA_NAMEs as inline asm inputs [PR113699]

Similar problem to calls with uninitialized large/huge _BitInt SSA_NAME
arguments, var_to_partition will not work for those, but unlike calls
where we just create a new uninitialized SSA_NAME here we need to change
the inline asm input to be an uninitialized VAR_DECL.

2024-02-02  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/113699
	* gimple-lower-bitint.cc (bitint_large_huge::lower_asm): Handle
	uninitialized large/huge _BitInt SSA_NAME inputs.

	* gcc.dg/bitint-81.c: New test.