Migrate libGLESv2 to ndk_library.

Test: make checkbuild
Bug: http://b/30465923
Change-Id: I62e108bdd27b6dc40fdf7ede7d579a286cbf3b9b
diff --git a/opengl/Android.bp b/opengl/Android.bp
index a21d6de..9acd2a2 100644
--- a/opengl/Android.bp
+++ b/opengl/Android.bp
@@ -26,6 +26,13 @@
     srcs: ["include/GLES/**/*.h"],
 }
 
+ndk_headers {
+    name: "libGLESv2_headers",
+    from: "include",
+    to: "",
+    srcs: ["include/GLES2/**/*.h"],
+}
+
 subdirs = [
     "*",
 ]