Fix trivial compiler warnings

Test: Compile & executed many of the tests on Marlin
Change-Id: I2d88922c5dcc88de0394c5bfade02ca1dd9d7b60
diff --git a/opengl/tests/angeles/demo.c b/opengl/tests/angeles/demo.c
index 39d871e..30c3202 100644
--- a/opengl/tests/angeles/demo.c
+++ b/opengl/tests/angeles/demo.c
@@ -462,7 +462,7 @@
 // Called from the app framework.
 void appInit()
 {
-    int a;
+    unsigned int a;
 
     glEnable(GL_NORMALIZE);
     glEnable(GL_DEPTH_TEST);
@@ -492,7 +492,7 @@
 // Called from the app framework.
 void appDeinit()
 {
-    int a;
+    unsigned int a;
     for (a = 0; a < SUPERSHAPE_COUNT; ++a)
         freeGLObject(sSuperShapeObjects[a]);
     freeGLObject(sGroundPlane);