[BOLT][TEST] Split runtime tests into test/runtime folder

Summary:
Create bolt/test/runtime folder and move tests that execute the binary.
Move lit.local.cfg with host_arch check to the corresponding folder.
Addresses issue facebookincubator/BOLT#132.

AArch64/tls.c shows a different behavior with clang hence marked as XFAIL

TODO: add a check for non-exec tests for a corresponding LLVM_TARGETS_TO_BUILD.

(cherry picked from FBD31132234)