dev-libs/libofx: fix RDEPEND on libxmlpp

dev-libs/libofx: fix RDEPEND on libxmlpp

	* Moves dependency on dev-cpp/libxmlpp:2.6 from DEPEND to RDEPEND
	* Add BDEPEND
	* Remove 'touch INSTALL' in src_prepare and patch Makefile.am instead
	* Don't install static lib if USE flag is not set
	* Adds patch from Alexandre Ferreira on b.g.o to install DTD correctly

Thanks to Alexandre Ferreira for the fix on DTD and DCL files.

Suggested-by: Alexandre Ferreira <alexandref75@gmail.com>
Closes: https://bugs.gentoo.org/692658
Closes: https://bugs.gentoo.org/692664
Package-Manager: Portage-2.3.72, Repoman-2.3.17
Signed-off-by: Bernd Waibel <waebbl@gmail.com>
Closes: https://github.com/gentoo/gentoo/pull/12758
Signed-off-by: Joonas Niilola <juippis@gentoo.org>