Update Makefiles to disable keyword-macro warning in tests

To make private methos avilable to unit tests, it is a common practice to redefine the private keyword.
While GCC doesn't carea bout this, older clang versions don't support this behavior and issue a warning.
As all warnings are converted into errors, this waring breaks the build. To allow the intended behavior
during testing, the -Wno-key-macro flag is added.

Author: mmuesly

src/Makefile

@@ -18,7 +18,6 @@ DIRS = analyses \
        langapi \
        linking \
        memory-analyzer \
-       memory-models \
        pointer-analysis \
        solvers \
        util \