Revert "ARM: mark missing functions from RTABI"

This reverts commit r215863.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216324 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "ARM: improve RTABI 4.2 conformance on Linux"

This reverts commit r215862 due to nightly failures.  Will work on getting a
reduced test case, but I wanted to get our bots green in the meantime.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216325 91177308-0d34-0410-b5e6-96231b3b80d8