Add a per target max vector alignment field (e.g., 32-byte alignment for x86 due to
AVX).  Currently, if no aligned attribute is specified the alignment of a vector is
inferred from its size.  Thus, very large vectors will be over-aligned with no 
benefit.  Target owners should set this target max.

llvm-svn: 160209
diff --git a/clang/lib/Basic/TargetInfo.cpp b/clang/lib/Basic/TargetInfo.cpp
index 8c49486..db5941a 100644
--- a/clang/lib/Basic/TargetInfo.cpp
+++ b/clang/lib/Basic/TargetInfo.cpp
@@ -47,6 +47,7 @@
   LargeArrayMinWidth = 0;
   LargeArrayAlign = 0;
   MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 0;
+  MaxVectorAlign = 0;
   SizeType = UnsignedLong;
   PtrDiffType = SignedLong;
   IntMaxType = SignedLongLong;