Replace NULL macros with nullptr literals.

Change-Id: I918c40879aa547438f77e7d1a95fa2aa33bec398
diff --git a/rsFont.h b/rsFont.h
index 71e6fb4..bc343c1 100644
--- a/rsFont.h
+++ b/rsFont.h
@@ -74,7 +74,7 @@
     }
 
     static Font * create(Context *rsc, const char *name, float fontSize, uint32_t dpi,
-                         const void *data = NULL, uint32_t dataLen = 0);
+                         const void *data = nullptr, uint32_t dataLen = 0);
 
 protected:
 
@@ -85,8 +85,8 @@
     // Last two variables are the initial pen position
     void renderUTF(const char *text, uint32_t len, int32_t x, int32_t y,
                    uint32_t start, int32_t numGlyphs,
-                   RenderMode mode = FRAMEBUFFER, Rect *bounds = NULL,
-                   uint8_t *bitmap = NULL, uint32_t bitmapW = 0, uint32_t bitmapH = 0);
+                   RenderMode mode = FRAMEBUFFER, Rect *bounds = nullptr,
+                   uint8_t *bitmap = nullptr, uint32_t bitmapW = 0, uint32_t bitmapH = 0);
 
     void invalidateTextureCache();
     struct CachedGlyphInfo
@@ -118,7 +118,7 @@
     uint32_t mDpi;
 
     Font(Context *rsc);
-    bool init(const char *name, float fontSize, uint32_t dpi, const void *data = NULL, uint32_t dataLen = 0);
+    bool init(const char *name, float fontSize, uint32_t dpi, const void *data = nullptr, uint32_t dataLen = 0);
 
     virtual void preDestroy() const;
     FT_FaceRec_ *mFace;
@@ -149,8 +149,8 @@
     void renderText(const char *text, uint32_t len, int32_t x, int32_t y,
                     uint32_t startIndex = 0, int numGlyphs = -1,
                     Font::RenderMode mode = Font::FRAMEBUFFER,
-                    Font::Rect *bounds = NULL,
-                    uint8_t *bitmap = NULL, uint32_t bitmapW = 0, uint32_t bitmapH = 0);
+                    Font::Rect *bounds = nullptr,
+                    uint8_t *bitmap = nullptr, uint32_t bitmapW = 0, uint32_t bitmapH = 0);
 
     void measureText(const char *text, uint32_t len, Font::Rect *bounds);