gccrs: Fix ICE when array elements are not a value

gccrs: Fix ICE when array elements are not a value

We need to check for error_mark_node when doing adjustments from coercion
sites otherwise we hit assetions as part of the coercion. That fixes the
ICE but the reason for the error_mark_node is because the array element
value.

Fixes Rust-GCC#3567

gcc/rust/ChangeLog:

	* backend/rust-compile-expr.cc (CompileExpr::array_value_expr): add value chk for array expr

gcc/testsuite/ChangeLog:

	* rust/compile/issue-3567.rs: New test.

Signed-off-by: Philip Herron <herron.philip@googlemail.com>