https://github.com/libretro/RetroArch/commit/3162b6a4386cee72af5539849d24a35cfe7652a2
https://bugs.gentoo.org/960043
Fix build with disable-pipewire on systems with pipewire installed

On systems where pipewire is installed but the build is configured with
--disable-pipewire, HAVE_PIPEWIRE_STABLE is set to 1 while HAVE_PIPEWIRE
is 0. Checking only HAVE_PIPEWIRE_STABLE leads to a build failure.
--- a/camera/camera_driver.c
+++ b/camera/camera_driver.c
@@ -55,7 +55,7 @@ const camera_driver_t *camera_drivers[] = {
 #ifdef HAVE_V4L2
    &camera_v4l2,
 #endif
-#ifdef HAVE_PIPEWIRE_STABLE
+#if defined(HAVE_PIPEWIRE) && defined(HAVE_PIPEWIRE_STABLE)
    &camera_pipewire,
 #endif
 #ifdef EMSCRIPTEN