[tools][llvm-lipo] Fix off-by-one error in command-line argument parsing

makeArrayRef(argv + 1, argc) -> makeArrayRef(argv + 1, argc - 1)
The previous behavior resulted in propagation of the null pointer
into later stages of arguments parsing instead of being automatically
handled by the existing check of MissingArgumentCount.

Test plan: ninja check-all

Differential revision: https://reviews.llvm.org/D132418