- Makefile: export PATH=${DESTDIR}/bin:$(PATH) and (DY)LD_LIBRARY_PATH, to make sure our local copies of built executables and libraries are used.
 - Makefile: use find expression in target 'yosys-svgviewer' to find svgviewer binary (qmake will build into .app package on OSX).
 - Makefile: make 'test' target dependent on $(TARGETS) and $(EXTRA_TARGETS) to make sure that minisat is built.
 - Makefile: fix typo in LDFLAGS: obviously -L, not -I is required here