Makefile: add 'make uninstall'

Makefile: add 'make uninstall'

An uninstall option, in addition to RPM install/uninstall, is arguably
quite convenient. Yet, Makefiles usually do not provide an 'uninstall'
target since that would require recording an installation manifest and
custom logic for removal.

However, meson has an internal feature doing precisely that.

This change invokes the meson uninstall feature via "make uninstall".

Signed-off-by: Simon A. F. Lund <simon.lund@samsung.com>