Add missing KeyDrawParams default constructor to fix build

Change-Id: Id2ae9e4085b4137c961b5202e0822d484dd71e8e
diff --git a/java/src/com/android/inputmethod/keyboard/internal/KeyDrawParams.java b/java/src/com/android/inputmethod/keyboard/internal/KeyDrawParams.java
index 43b3237..203bab6 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/KeyDrawParams.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/KeyDrawParams.java
@@ -43,6 +43,8 @@
 
     public int mAnimAlpha;
 
+    public KeyDrawParams() {}
+
     private KeyDrawParams(final KeyDrawParams copyFrom) {
         mTypeface = copyFrom.mTypeface;