Revert "In visitSTORE, always use FindBetterChain, rather than only when UseAA is enabled."

This reverts commit r296252 until 256-bit operations are more efficiently generated in X86.

llvm-svn: 296279
diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
index 518417d..5f021a1 100644
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -850,7 +850,7 @@
   MinFunctionAlignment = 0;
   PrefFunctionAlignment = 0;
   PrefLoopAlignment = 0;
-  GatherAllAliasesMaxDepth = 18;
+  GatherAllAliasesMaxDepth = 6;
   MinStackArgumentAlignment = 1;
   // TODO: the default will be switched to 0 in the next commit, along
   // with the Target-specific changes necessary.