This reverts commit c56514f21b2cf08eaa7ac3a57ba4ce403a9c8956. This
commit adds global state that is shared between clang driver and clang
cc1, which is not correct when clang is used with `-fno-integrated-cc1`
option (no integrated cc1). The -march and -mtune option needs to be
properly passed through cc1 command-line and stored in TargetInfo.
42c9354a92