Remove CMAKE_BUILD_WITH_INSTALL_RPATH=TRUE for OSX
Remove CMAKE_BUILD_WITH_INSTALL_RPATH=TRUE for OSX

This option was breaking the out-of-the-box build on OSX, specifically
by breaking each test so it couldn't find libpdalcpp.dylib.

As far as I understand RPATH, CMAKE_BUILD_WITH_INSTALL_RPATH meant that
the libraries and executables in our build tree (un-installed) would
have their rpaths set to CMAKE_INSTALL_PREFIX directories. On a system
w/o an installed PDAL, this meant that each test executable had no
libpdalcpp.dylib to dynamically link against.

Removing this line falls back to the setting from above, where
CMAKE_BUILD_WITH_INSTALL_RPATH was set to FALSE (IMO the correct
setting).

mtCarto/PDAL,lucadelu/PDAL,mpgerlek/PDAL-old,DougFirErickson/PDAL,Sciumo/PDAL,boundlessgeo/PDAL,radiantbluetechnologies/PDAL,Sciumo/PDAL,Sciumo/PDAL,DougFirErickson/PDAL,DougFirErickson/PDAL,lucadelu/PDAL,Sciumo/PDAL,boundlessgeo/PDAL,mtCarto/PDAL,lucadelu/PDAL,radiantbluetechnologies/PDAL,lucadelu/PDAL,radiantbluetechnologies/PDAL,jwomeara/PDAL,jwomeara/PDAL,radiantbluetechnologies/PDAL,jwomeara/PDAL,mpgerlek/PDAL-old,boundlessgeo/PDAL,boundlessgeo/PDAL,mtCarto/PDAL,DougFirErickson/PDAL,jwomeara/PDAL,mtCarto/PDAL,mpgerlek/PDAL-old,mpgerlek/PDAL-old