Remove a pointless LLVM_CONSTEXPR. NFC.

llvm-svn: 279702
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 425aeac..c2de06b 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -653,7 +653,7 @@
 
   assert(!TTP->getRequiresClause() &&
          "Unexpected requires-clause on template template-parameter");
-  LLVM_CONSTEXPR Expr *const CanonRequiresClause = nullptr;
+  Expr *const CanonRequiresClause = nullptr;
 
   TemplateTemplateParmDecl *CanonTTP
     = TemplateTemplateParmDecl::Create(*this, getTranslationUnitDecl(),