Remove LLVM_CONSTEXPR.

Summary: With MSVC 2013 and GCC < 4.8 gone, we can use the "constexpr" keyword.

Reviewers: bkramer, mehdi_amini

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D25901

llvm-svn: 284947
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfAccelTable.h b/llvm/lib/CodeGen/AsmPrinter/DwarfAccelTable.h
index 4d81441..05ac1cb 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfAccelTable.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfAccelTable.h
@@ -126,8 +126,7 @@
     uint16_t type; // enum AtomType
     uint16_t form; // DWARF DW_FORM_ defines
 
-    LLVM_CONSTEXPR Atom(uint16_t type, uint16_t form)
-        : type(type), form(form) {}
+    constexpr Atom(uint16_t type, uint16_t form) : type(type), form(form) {}
 #ifndef NDEBUG
     void print(raw_ostream &O) {
       O << "Type: " << dwarf::AtomTypeString(type) << "\n"