Fix testcase module path

Fix testcase module path

Those tests are coming from libcore and module inlining was wrong, in
libcore there was a use declaration to import those modules which was
missing here.

gcc/testsuite/ChangeLog:

	* rust/compile/issue-2330.rs: Use complete path from crate root.
	* rust/compile/issue-1901.rs: Likewise.
	* rust/compile/issue-1981.rs: Likewise.
	* rust/compile/iterators1.rs: Likewise.
	* rust/compile/sizeof-stray-infer-var-bug.rs: Likewise.
	* rust/compile/for-loop1.rs: Likewise.
	* rust/compile/for-loop2.rs: Likewise.
	* rust/compile/torture/builtin_abort.rs: Likewise.
	* rust/compile/torture/uninit-intrinsic-1.rs: Likewise.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>