math/cocoalib: Update to 0.99710

Also:

• build the port by patching existing Makefiles instead of copying a new one from ${FILESDIR} in the hope that this eases maintainance;
• change the SMALLDEG option so that it now applies a patch conditionally instead of using ${REINPLACE_CMD}.

Approved by: gerald (mentor)
Differential Revision: https://reviews.freebsd.org/D25234