Export _Unwind_Complete and _Unwind_VRS_Pop from arm's libgcc_s

Apparently some ports on arm require these symbols, and while they were
available in llvm's libunwind, they were never exported via the arm
specific Symbol.map. Put them in the same version block as gcc does
(GCC_3.5).

Reported by: Robert Clausecker <fuz_at_fuz.su>
MFC after: 3 days

(cherry picked from commit 8e5bcff58b77f8108b2bef0f1d113a91aef502a4)