Support for 64-bit location_t: Backend parts

Support for 64-bit location_t: Backend parts

A few targets have been using "unsigned int" function arguments that need to
receive a "location_t". Change to "location_t" to prepare for the
possibility that location_t can be configured to be a different type.

gcc/ChangeLog:

	* config/aarch64/aarch64-c.cc (aarch64_resolve_overloaded_builtin):
	Change "unsigned int" argument to "location_t".
	* config/avr/avr-c.cc (avr_resolve_overloaded_builtin): Likewise.
	* config/riscv/riscv-c.cc (riscv_resolve_overloaded_builtin): Likewise.
	* target.def: Likewise.
	* doc/tm.texi: Regenerate.