[CMake] Pass DYLD_LIBRARY_PATH as CMake variable instead of as envar

On OS X 10.11 System Integrity Protection prevents the DYLD environment variables from being set on system binaries. To work around this r276710 accepts DYLD_LIBRARY_PATH as a CMake variable and sets it directly on the archiver commands.

To make this work with bootstrapping we need to set DYLD_LIBRARY_PATH to the current stage's library directory and pass that into the next stage's configuration.

llvm-svn: 276711