The regex being overspecified meant that host tests were not properly
replacing the dummy.o when linking, meaning all of the tests that were
running were running nothing but `int main() {}`.
The good news is that there weren't any failing tests hiding behind
this on Linux.
Change-Id: I9bea82ff1fefdf156d68a58689e532807c8d999b
Use LOCAL_CXX with a dummy compiler to determine the build/link flags
the build system will use to build a typical Android executable. This
both prevents test failures when the build system simply goes out of
sync with the old, hard coded flags, and helps us catch new failures
introduced by build system changes ASAP.
Change-Id: I9a867ab49b7f2158070cf944c7a96084089a3718
