Support linking against dependencies with "-L -lfoo"

[springmeyer]

We should support building against osrm-backend deps that are referenced with -L -lfoo and also /path/to/foo.a. After Project-OSRM/osrm-backend#3130 all static libs will be provided in the libosrm.pc as /path/to/foo.a.

To be able to backport fixes from node-osrm master into the 5.4 branch a few more adjustments are needed to support -L -lfoo (which is what osrm-backend 5.4 is providing and what will be provided for users with shared libs as deps).