[externals/stb] only include JPEG functions, disable all others (#4179)

we use JPEG only with STB, dont need the others
which are included in the final binary, after gc+lto

this doesnt affect stb_dxt, which still includes all required BCn stuff

Signed-off-by: lizzie <lizzie@eden-emu.dev>

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4179
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>

src/core/hle/service/ns/read_only_application_control_data_interface.cpp

@@ -7,10 +7,12 @@
 #include <algorithm>
 #include <vector>
 #include <optional>
+#include <string>
+
+#define STBI_ONLY_JPEG 1
 #include <stb_image.h>
 #include <stb_image_resize.h>
 #include <stb_image_write.h>
-#include <string>
 
 #include "common/settings.h"
 #include "core/file_sys/control_metadata.h"