[C++] Use 'nullptr'. Target edition.

llvm-svn: 207197
diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
index 0f99ecc..153974e 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
@@ -31,7 +31,7 @@
 
 // Prepare value for the target space for it
 static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
-                                 MCContext *Ctx = NULL) {
+                                 MCContext *Ctx = nullptr) {
 
   unsigned Kind = Fixup.getKind();