Support Soong native coverage

Soong (or any other prebuilt) can provide a .gcnodir file using
LOCAL_PREBUILT_COVERAGE_ARCHIVE. Just like today, if one isn't provided
for static libraries, an empty one will be created for Make modules to
use.

Also fixes a problem I noticed including whole static libs having
coverage into static libs. It was trying to write to /WHOLE since
PRIVATE_INTERMEDIATES_DIR was not set.

Bug: 32749731
Test: See build/soong change for soong-side tests
Test: Enabled coverage of a soong static lib, then include it in a make
static lib with LOCAL_WHOLE_STATIC_LIBRARIES and ensure that the any
shared libraries using the make static lib get the embedded coverage
information.
Change-Id: I32762f099c9757074fec922ee4822f819c9ceaf5