init-mixed.c count

The variable isn't a counter so rename it, and use small values that
won't overflow a target with 16-bit int.  Since commit 2e806738bd
there is a possibility of running tests on such targets.

	* testsuite/ld-elf/init-mixed.c: Rename "count" to "order"
	and use values of 0 to 6 when checking init/fini order.