Log Message:
* This package uses C++, so add 'c++' to USE_LANGUAGES.
* Honor PKGMANDIR.
* Use LDFLAGS.Linux instead of an explicit test for ${OPSYS} == "Linux".

This fixes the bulk build problem reported in:

	http://mail-index.netbsd.org/pkgsrc-bulk/2006/06/20/0000.html