[libunwind][ARM] Improve unwinder stack usage - Make WMMX support optional

These registers are only available on a limited set of ARM targets (those
based on XScale). Other targets should not have to pay the cost of these.

This patch shaves off about ~300 bytes of stack usage and ~1KB of code-size.

Differential revision: http://reviews.llvm.org/D21991
Reviewers: bcraig, compnerd

Change-Id: I2d7a1911a193bd70b123e78747e1a7d1482463c7

git-svn-id: https://llvm.org/svn/llvm-project/libunwind/trunk@274744 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed
tree: 1e0ee6495e24d886c98e3f30b65a6bfb5829954e
  1. cmake/
  2. include/
  3. src/
  4. test/
  5. .arcconfig
  6. .clang-format
  7. CMakeLists.txt