Remove unecessary exported symbols from libhwui.so

Test: compiles and links
Bug: 150782769
Change-Id: Ib49c1bf914b6bfaad1fb29371115df7c9eec08d2
diff --git a/libs/hwui/renderthread/RenderTask.h b/libs/hwui/renderthread/RenderTask.h
index c56a357..3e3a381 100644
--- a/libs/hwui/renderthread/RenderTask.h
+++ b/libs/hwui/renderthread/RenderTask.h
@@ -45,12 +45,12 @@
  * malloc/free churn of small objects?
  */
 
-class ANDROID_API RenderTask {
+class RenderTask {
 public:
-    ANDROID_API RenderTask() : mNext(nullptr), mRunAt(0) {}
-    ANDROID_API virtual ~RenderTask() {}
+    RenderTask() : mNext(nullptr), mRunAt(0) {}
+    virtual ~RenderTask() {}
 
-    ANDROID_API virtual void run() = 0;
+    virtual void run() = 0;
 
     RenderTask* mNext;
     nsecs_t mRunAt;  // nano-seconds on the SYSTEM_TIME_MONOTONIC clock