Move the code which knows how to get information about the shared

cache from ObjectFileMachO (very wrong place) to the DynamicLoader
plugins (better place).  Not much change to the code itself, although
the old ObjectFileMachO method would try both the new dyld SPI and
reading the dyld_all_image_infos structure.  In the new methods,
I've separated those into the appropriate DynamicLoader plugins.

llvm-svn: 277088