Replace LLVM_ALIGNAS with just alignas.

Various places in Clang and LLVM are already using alignas; it seems
our minimum host configuration now requires it.

llvm-svn: 337330
diff --git a/clang/lib/CodeGen/CGCleanup.h b/clang/lib/CodeGen/CGCleanup.h
index 5530350..93be3e6 100644
--- a/clang/lib/CodeGen/CGCleanup.h
+++ b/clang/lib/CodeGen/CGCleanup.h
@@ -230,7 +230,7 @@
 };
 
 /// A cleanup scope which generates the cleanup blocks lazily.
-class LLVM_ALIGNAS(/*alignof(uint64_t)*/ 8) EHCleanupScope : public EHScope {
+class alignas(8) EHCleanupScope : public EHScope {
   /// The nearest normal cleanup scope enclosing this one.
   EHScopeStack::stable_iterator EnclosingNormal;