c: fix wrong encoding for zero-sized arrays [PR125618]

c: fix wrong encoding for zero-sized arrays [PR125618]

This reverts one change from 106970adca69c9c577e6c75f4e69a08cd9ea2df0
that replaced build_range_type with build_index_type.  In the function
complete_array_type this breaks zero-sized arrays created from an empty
initializer which there are represented using the C++ FE way [0, -1]
causing issues on 32 bit architectures.

After this partial revert this representation remains inconsistent to
the usual C FE representation [0, NULL_TREE] (as before by change).

	PR c/125618

gcc/c-family/ChangeLog:
	* c-common.cc (complete_array_type): Change back to using
	build_range_type.