Improve build: LDFLAGS.

Linker must be passed LDFLAGS for some distributions, as CXXFLAGS should
not normally contain any linker flags (may fail if passed to
compile-only invocations).

Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>
Merge pull request #3 from robbat2/master

Improve build: LDFLAGS
Merge ejt/master