Blender Git Loki

macOS: Portable builds with dynamic libraries.

For Blender.app: dropping libomp.dylib next to Blender executable is
enough for it getting picked up since `@executable_path` is an rpath.

For non-distributed binaries datatoc, makesdna, tests etc, code for
copying libomp.dylib to build folder is removed and replaced by
CMake's rpath option for *build* tree.

For bpy.so, the post build rpath change has also been replaced by CMake
rpath option for *install* tree.

Since -id has been changed in D11748, remove the
`install_name_tool -change ...` command.

Any dylib can just be dropped at `MAC_BLENDER_TARGET_DYLIBS_DIR`
hereafter. Appending dylib path to `CMAKE_BUILD_RPATH` will be needed
for datatoc etc if linked against one (instead of copying the
dylibs around).

Reviewed By: #platform_macos, brecht
Differential Revision: https://developer.blender.org/D11997