[Perf] (MG_Backend/DirectGLES, MG_Impl): cache link-time lookups, bound unit scans, honor eglSwapInterval

- BackendProgramObjectImpl::CacheResourceLocations resolves every
  glGetUniformBlockIndex / glGetUniformLocation string query once per
  link and establishes the block binding points there. Per draw,
  BindCurrentProgramWithResources now uses the cached indices, re-issues
  glUniform1i only when a sampler's unit actually changed (program state
  persists), uploads the global UBO only when its content version moved,
  and skips redundant glUseProgram binds (guard reset on program-name
  reuse, MakeCurrent, and every explicit glUseProgram(0)). The caches are
  invalidated through ProgramObject's link version, which also makes a
  relinked program finally re-sync its backend program.
- Track a texture-unit high-water mark (fed by glBindTexture /
  glBindTextureUnit / glBindSampler / glBindImageTexture) so the two
  per-draw unit scans (MAX_TEXTURE_IMAGE_UNITS is 192) and the
  texture-deletion unbind loop only walk units that were ever touched.
- Forward the app's eglSwapInterval to the native EGL surface through a
  new BackendObject::SetEGLSwapInterval hook (applied immediately when
  the surface exists, otherwise deferred to surface creation /
  MakeCurrent). "VSync off" finally reaches the hardware - DirectGLES
  was hard-locked to the display refresh before.

The driver-side cost of the per-draw string lookups was about half of a
30% Adreno driver hotspot; libMobileGL's share of the vanilla render
thread fell from 22% to 9% (simpleperf, Adreno 830).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

MobileGL/MG_Impl/EGLImpl/EGLImpl.cpp

@@ -415,7 +415,17 @@ namespace MobileGL::MG_Impl::EGLImpl {
         if (!state) {
             return EGL_FALSE;
         }
-        return state->SwapInterval(dpy, interval) ? EGL_TRUE : EGL_FALSE;
+        if (!state->SwapInterval(dpy, interval)) {
+            return EGL_FALSE;
+        }
+        // Forward the request to the backend's native presentation path; without this
+        // the app's vsync setting only ever reaches MobileGL's shadow state and the
+        // native surface stays at the driver default (interval 1 = always vsynced).
+        auto* backendObject = GetBackendObject(state);
+        if (backendObject) {
+            backendObject->SetEGLSwapInterval(static_cast<Int>(interval));
+        }
+        return EGL_TRUE;
     }
 
     EGLSurface CreatePbufferSurface(EGLDisplay dpy, EGLConfig config, const EGLint* attrib_list) {