We will link to boehm inside of the test suite if it depends on libexpr
but we don't need it for other tests.
For anything linking to libexpr internally, just like externally, it
needs to link to boehm.
Likewise with kj and libutil (or really any lix), so we should just make
it automatic.
Change-Id: I2bb9ec4668e6ff741b4139fdce167f278eb71c7e
Jade Lovelace
1eafc7dbf4