Issues with cmake on MacOS with Homebrew

[rpgoldman]

Homebrew organizes the directories for coinor differently than the popf cmakefiles expect. In particular, instead of pushing all the header files into a single coin directory, they go into <module>/coin/ (e.g., cbc/coin/). I tweaked the Find<foo>.cmake files to make cmake find the libraries, but I don't use cmake myself, so I don't know how to make the changed versions be alternative locations. See attached git diff.

Oh, yes, and the OSI config header was OsiConfig.h instead of osi_config.h