Auto merge of #133955 - bjorn3:cc_pass_arch_only, r=ChrisDenton

Pass the arch rather than full target name to windows_registry::find_tool

The full target name can be anything with custom target specs. Passing just the arch wasn't possible before cc 1.2, but is now thanks to rust-lang/cc-rs#1285.

try-job: i686-msvc

Author: bors