Revert "[libcxxabi][ARM] Make CXX_end_cleanup compatible with Armv6-M"

This reverts commit 3255578ee1dbb5561025ac89cd33ba08e8f26efb.

Failed buildbot's Armv7 builds:
https://lab.llvm.org/buildbot/#/builders/60/builds/5303

GitOrigin-RevId: c0d22dd0e745868a12662b843b9653fdad1154d8
1 file changed