[opengl] Modernize codebase by replacing NULL with nullptr

Fixes -Wzero-as-null-pointer-constant warning.

Test: m
Bug: 68236239
Change-Id: Ia2f91707b277954d5105f6fdb489caad9ef8848c
diff --git a/opengl/libs/EGL/egldefs.h b/opengl/libs/EGL/egldefs.h
index 9858276..299d8f7 100644
--- a/opengl/libs/EGL/egldefs.h
+++ b/opengl/libs/EGL/egldefs.h
@@ -37,7 +37,7 @@
         GLESv2_INDEX = 1
     };
 
-    inline egl_connection_t() : dso(0) { }
+    inline egl_connection_t() : dso(nullptr) { }
     void *              dso;
     gl_hooks_t *        hooks[2];
     EGLint              major;