LibGL: Implement glDepthMask

Author: https://github.com/sunverwerth
Commit: 5f863016ca
Pull-request: https://github.com/SerenityOS/serenity/pull/9382
Reviewed-by: https://github.com/alimpfard

Userland/Libraries/LibGL/GLUtils.cpp

@@ -89,3 +89,8 @@ void glGetFloatv(GLenum pname, GLfloat* params)
 {
     g_gl_context->gl_get_floatv(pname, params);
 }
+
+void glDepthMask(GLboolean flag)
+{
+    g_gl_context->gl_depth_mask(flag);
+}