Add support for `-D` and `-U` options for llvm-libtool-darwin. `-D` allows for using zero for timestamps and UIDs/GIDs. `-U` allows for using actual timestamps and UIDs/GIDs. Reviewed by jhenderson, smeenai Differential Revision: https://reviews.llvm.org/D84209  | 
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| .. | ||
| CMakeLists.txt | ||
| LLVMBuild.txt | ||
| llvm-libtool-darwin.cpp | ||