expand: Fix up LTO ICE with COMPOUND_LITERAL_EXPR [PR99849]

expand: Fix up LTO ICE with COMPOUND_LITERAL_EXPR [PR99849]

The gimplifier optimizes away COMPOUND_LITERAL_EXPRs, but they can remain
in the form of ADDR_EXPR of COMPOUND_LITERAL_EXPRs in static initializers.
By the TREE_STATIC check I meant to check that the underlying decl of
the compound literal is a global rather than automatic variable which
obviously can't be referenced in static initializers, but unfortunately
with LTO it might end up in another partition and thus be DECL_EXTERNAL
instead.

2021-04-10  Jakub Jelinek  <jakub@redhat.com>

	PR lto/99849
	* expr.c (expand_expr_addr_expr_1): Test is_global_var rather than
	just TREE_STATIC on COMPOUND_LITERAL_EXPR_DECLs.

	* gcc.dg/lto/pr99849_0.c: New test.