Un-revert the environ copy in ProgramTest after fixing it on OS X

This was r180041 and r180046, which was reverted in r180066.
Re-committing this should fix the dragonegg bootstrap, which I presume
needs LD_LIBRARY_PATH to be propagated to the child.

Tested on Linux, Windows, and Mac OS 10.6.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180099 91177308-0d34-0410-b5e6-96231b3b80d8