rustc: Fix omission of bytecode in staticlibs

The name of the file changed awhile back and this spot wasn't updated to
continue ignoring the bytecode from rlibs when copying into staticlibs.
auto merge of #13569 : alexcrichton/rust/ignore-bytecode, r=brson

The name of the file changed awhile back and this spot wasn't updated to
continue ignoring the bytecode from rlibs when copying into staticlibs.