spirv/vtn_cfg.c: Include util/debug.h for env_var_as_boolean.

Fixes https://gitlab.freedesktop.org/mesa/mesa/-/issues/3414

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6331>

src/compiler/spirv/vtn_cfg.c

diff --git a/src/compiler/spirv/vtn_cfg.c b/src/compiler/spirv/vtn_cfg.c
index 074f61b..83ca13b 100644
--- a/src/compiler/spirv/vtn_cfg.c
+++ b/src/compiler/spirv/vtn_cfg.c
@@ -24,6 +24,7 @@
 #include "vtn_private.h"
 #include "spirv_info.h"
 #include "nir/nir_vla.h"
+#include "util/debug.h"
 
 static struct vtn_block *
 vtn_block(struct vtn_builder *b, uint32_t value_id)