cgal-3.5.1: libraries link with libraries in working directory

[raphael-st (Raphael Straub)]

The CGAL libraries link with libraries in the working directory, e. g.

> otool -L /opt/local/lib/libCGAL_ImageIO.dylib 
/opt/local/lib/libCGAL_ImageIO.dylib:
	/opt/local/lib/libCGAL_ImageIO.4.dylib (compatibility version 4.0.0, current version 4.0.1)
	/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_gis_cgal/work/CGAL-3.5.1/lib/libCGAL.4.dylib (compatibility version 4.0.0, current version 4.0.1)
	/opt/local/lib/libgmpxx.4.dylib (compatibility version 7.0.0, current version 7.1.0)
	/opt/local/lib/libmpfr.1.dylib (compatibility version 4.0.0, current version 4.2.0)
	/opt/local/lib/libgmp.10.dylib (compatibility version 11.0.0, current version 11.1.0)
	/opt/local/lib/libboost_thread-mt.dylib (compatibility version 0.0.0, current version 0.0.0)
	/System/Library/Frameworks/AGL.framework/Versions/A/AGL (compatibility version 1.0.0, current version 1.0.0)
	/System/Library/Frameworks/OpenGL.framework/Versions/A/OpenGL (compatibility version 1.0.0, current version 1.0.0)
	/usr/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.3)
	/usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 7.4.0)
	/usr/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1.0.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 111.1.4)

The attached patch fixes this by using the cmake port group. In addition the patch adds missing dependencies on zlib and gmp.

[Veence (Vincent)]

Give me one or two days to test it and I will commit it.

[raphael-st (Raphael Straub)]

Fixed in r69518; see #25530.