Replace NULL with nullptr

Also fixed some lines that were too long, and a few other minor
details.

Change-Id: I6efba5fb6e03eb5d0a300fddb2a75bf8e2f175cb
diff --git a/compiler/jni/quick/jni_compiler.cc b/compiler/jni/quick/jni_compiler.cc
index 2402ea5..6f2cb25 100644
--- a/compiler/jni/quick/jni_compiler.cc
+++ b/compiler/jni/quick/jni_compiler.cc
@@ -152,9 +152,9 @@
     // References need placing in handle scope and the entry value passing
     if (ref_param) {
       // Compute handle scope entry, note null is placed in the handle scope but its boxed value
-      // must be NULL
+      // must be null.
       FrameOffset handle_scope_offset = main_jni_conv->CurrentParamHandleScopeEntryOffset();
-      // Check handle scope offset is within frame and doesn't run into the saved segment state
+      // Check handle scope offset is within frame and doesn't run into the saved segment state.
       CHECK_LT(handle_scope_offset.Uint32Value(), frame_size);
       CHECK_NE(handle_scope_offset.Uint32Value(),
                main_jni_conv->SavedLocalReferenceCookieOffset().Uint32Value());
@@ -243,9 +243,9 @@
   // 7. Iterate over arguments placing values from managed calling convention in
   //    to the convention required for a native call (shuffling). For references
   //    place an index/pointer to the reference after checking whether it is
-  //    NULL (which must be encoded as NULL).
+  //    null (which must be encoded as null).
   //    Note: we do this prior to materializing the JNIEnv* and static's jclass to
-  //    give as many free registers for the shuffle as possible
+  //    give as many free registers for the shuffle as possible.
   mr_conv->ResetIterator(FrameOffset(frame_size + main_out_arg_size));
   uint32_t args_count = 0;
   while (mr_conv->HasNext()) {
@@ -451,7 +451,7 @@
                                                  ArrayRef<const LinkerPatch>());
 }
 
-// Copy a single parameter from the managed to the JNI calling convention
+// Copy a single parameter from the managed to the JNI calling convention.
 static void CopyParameter(Assembler* jni_asm,
                           ManagedRuntimeCallingConvention* mr_conv,
                           JniCallingConvention* jni_conv,
@@ -469,7 +469,7 @@
   } else {
     CHECK(jni_conv->IsCurrentParamOnStack());
   }
-  // References need placing in handle scope and the entry address passing
+  // References need placing in handle scope and the entry address passing.
   if (ref_param) {
     null_allowed = mr_conv->IsCurrentArgPossiblyNull();
     // Compute handle scope offset. Note null is placed in the handle scope but the jobject