This patch removes --version as a clang -cc1 option.
clang --cc1 -version
remain valid. This behaviour is consistent with clang -cc1as.
Previously, clang -cc1 accepted both --version and -version, but
only -version was acted upon. The call
clang -cc1 --version
stalled without any message: --version was an accepted option but
triggered no action, and the driver waited for standard input.