[Fix] (MG_Impl): silently ignore program and shader name zero on delete

glDeleteProgram and glDeleteShader are the two entry points in the program/shader name
space where 0 is not "a name GL never handed out" but an explicit no-op: "if program is
zero, it is silently ignored" (GL 4.6 core 7.3, and 7.1 for shaders). Both went through
the shared name validator instead and recorded GL_INVALID_VALUE.

Only tests that never got as far as creating a program noticed, because they still run
their cleanup path: the five KHR-GL40.texture_gather.*-cube-array cases bail out of
Init with "GL_ARB_texture_cube_map_array not supported", then Cleanup deletes its
zero-initialised handles and the leftover error fails the case after the fact - the
downstream-error-misattribution shape. Every array-taking delete already skipped 0.

MobileGL/MG_Impl/GLImpl/Program/GL_Program.cpp

@@ -325,11 +325,16 @@ namespace MobileGL::MG_Impl::GLImpl {
     }
 
     void DeleteProgram_State(GLuint program) {
+        // "If program is zero, it is silently ignored" (GL 4.6 core 7.3) - unlike every
+        // other program entry point, where 0 is a name GL never handed out.
+        if (program == 0) return;
         if (!CheckProgramNameValidity(program)) return;
         MG_State::pGLContext->MarkProgramForDeletion(program);
     }
 
     void DeleteShader_State(GLuint shader) {
+        // Same silent-zero rule as glDeleteProgram (GL 4.6 core 7.1).
+        if (shader == 0) return;
         if (!CheckShaderNameValidity(shader)) return;
         MG_State::pGLContext->MarkShaderForDeletion(shader);
     }