toolchain: local develop_34 clang, compiler-rt, isl, lldb, llvm, polly

Summary: T18 is relevant

Test Plan: just puts these repos in the tree right now.

Reviewers: randall.rushing, synergy

Reviewed By: synergy

Differential Revision: http://review.codefirex.com/D544

Change-Id: I7336e668e3e880c334ed07abbc3e48c104481087