vulkan: fix uninitialized variables

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13892>

src/vulkan/util/vk_util.h

@@ -282,7 +282,7 @@ vk_spec_info_to_nir_spirv(const VkSpecializationInfo *spec_info,
 #define STACK_ARRAY_SIZE 8
 
 #define STACK_ARRAY(type, name, size) \
-   type _stack_##name[STACK_ARRAY_SIZE], *const name = \
+   type _stack_##name[STACK_ARRAY_SIZE] = {0}, *const name = \
       (size) <= STACK_ARRAY_SIZE ? _stack_##name : malloc((size) * sizeof(type))
 
 #define STACK_ARRAY_FINISH(name) \