[Feat] (MG_Impl, DirectGLES): advertise GL_ARB_get_program_binary with no binary format

glProgramParameteri is not core before GL 4.1, so in the 4.0 context the CTS runs it
only exists through GL_ARB_get_program_binary or GL_ARB_separate_shader_objects.
MobileGL advertised neither, so dEQP's loader left the entry point null - and
KHR-GL40.api.coverage, which registers glProgramParameteri from GL 3.2 upwards, called
straight through the null pointer and took the process down.

GL_NUM_PROGRAM_BINARY_FORMATS was already 0, and the extension explicitly allows an
implementation to support no binary format at all; that is the honest state of things
here, since a MobileGL program is a glslang link plus a per-backend translation with no
serialised form. So the extension is advertised for what it really provides:
glProgramParameteri stores GL_PROGRAM_BINARY_RETRIEVABLE_HINT (reported back by
glGetProgramiv alongside a GL_PROGRAM_BINARY_LENGTH of zero), glGetProgramBinary is the
INVALID_OPERATION the spec requires when that length is zero, and glProgramBinary
rejects every format with INVALID_ENUM and leaves the program's LINK_STATUS false.

Applications that ask for a binary get the documented "no formats" answer and fall
back, which is what they already had to do - only now they can ask.

MobileGL/MG_Backend/DirectGLES/BackendObject_DirectGLES.cpp

@@ -910,7 +910,11 @@ namespace MobileGL::MG_Backend::DirectGLES {
                                           // picks a whole different shader for draw_buffers without
                                           // explicit_attrib_location. DirectVulkan advertises both.
                                           E_GL_ARB_explicit_attrib_location, E_GL_ARB_texture_multisample,
-                                          E_GL_ARB_shader_image_size};
+                                          E_GL_ARB_shader_image_size,
+                                          // Advertised with GL_NUM_PROGRAM_BINARY_FORMATS = 0, which the
+                                          // extension explicitly permits. It is also the only thing that
+                                          // exposes glProgramParameteri before GL 4.1.
+                                          E_GL_ARB_get_program_binary};
         // Only advertised when the device driver actually has usable timer queries
         // (GL_EXT_disjoint_timer_query plus its entry points) and the
         // MOBILEGL_DISABLE_TIMERQUERY escape hatch is off.