When we create a precompiled preamble, don't copy the

CompilerInvocation on the stack, because other objects (e.g., the
CompilerInstance) maintain an intrusive reference-counted pointer to
the CompilerInvocation. This doesn't matter in the normal case,
because we take back the CompilerInvocation. However, during crash
recovery, this leads to us trying to free an object on the stack, and
hilarity ensues. Fixes <rdar://problem/9652540>.

llvm-svn: 134245