BaseTools CLANG35: use linux-gnu target triplets explicitly

BaseTools CLANG35: use linux-gnu target triplets explicitly

Since we are combining Clang with the GNU linker, make that explicit in
the target triplet. This affects certain builtin defines and other compiler
behavior that may be unspecified otherwise.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19583 6f19259b-4bc3-4df7-8a09-765794883524