Revert "[ARM] Set default alignment to 64bits"

This reverts commit r367119.

This broke several bots:

http://lab.llvm.org:8011/builders/clang-atom-d525-fedora-rel/builds/26891/steps/ninja%20check%201/logs/FAIL%3A%20Clang%3A%3Aexception-alignment.cpp
http://green.lab.llvm.org/green/job/clang-stage1-cmake-RA-incremental/245/consoleFull

llvm-svn: 367166
diff --git a/clang/lib/Basic/Targets/ARM.cpp b/clang/lib/Basic/Targets/ARM.cpp
index 3ae2091..c6834b9 100644
--- a/clang/lib/Basic/Targets/ARM.cpp
+++ b/clang/lib/Basic/Targets/ARM.cpp
@@ -309,9 +309,8 @@
   setAtomic();
 
   // Maximum alignment for ARM NEON data types should be 64-bits (AAPCS)
-  // as well the default alignment
   if (IsAAPCS && (Triple.getEnvironment() != llvm::Triple::Android))
-    DefaultAlignForAttributeAligned = MaxVectorAlign = 64;
+    MaxVectorAlign = 64;
 
   // Do force alignment of members that follow zero length bitfields.  If
   // the alignment of the zero-length bitfield is greater than the member