[texture_cache] Fix a rare visual corruption under specific conditions (#3986)

This fixes a rare visual corruption that can occur under specific conditions depending on the hardware used.

This bug is known to affect the loading screens in The Legend of Zelda: Tears of the Kingdom.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3986
Reviewed-by: Lizzie <lizzie@eden-emu.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>

src/video_core/texture_cache/texture_cache.h

@@ -128,6 +128,7 @@ void TextureCache<P>::RunGarbageCollector() {
         if (num_iterations == 0) {
             return true;
         }
+        --num_iterations;
         auto& image = slot_images[image_id];
         if (True(image.flags & ImageFlagBits::IsDecoding)) {
             return false;
@@ -136,7 +137,6 @@ void TextureCache<P>::RunGarbageCollector() {
         if ((!aggressive_mode && True(image.flags & ImageFlagBits::CostlyLoad)) || (!high_priority_mode && must_download)) {
             return false;
         }
-        --num_iterations;
         if (must_download) {
             auto map = runtime.DownloadStagingBuffer(image.unswizzled_size_bytes);
             const auto copies = FixSmallVectorADL(FullDownloadCopies(image.info));