gallium/util: add some extern "C" guards

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13285>

src/gallium/auxiliary/util/u_async_debug.h

@@ -37,6 +37,10 @@
 #include "util/u_debug.h"
 #include "util/simple_mtx.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 struct util_debug_message {
    unsigned *id;
    enum pipe_debug_type type;
@@ -71,4 +75,8 @@ u_async_debug_drain(struct util_async_debug_callback *adbg,
       _u_async_debug_drain(adbg, dst);
 }
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* UTIL_ASYNC_DEBUG_H */

src/gallium/auxiliary/util/u_live_shader_cache.h

@@ -52,6 +52,10 @@
 #include "util/simple_mtx.h"
 #include "pipe/p_state.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 struct util_live_shader_cache {
    simple_mtx_t lock;
    struct hash_table *hashtable;
@@ -88,4 +92,8 @@ util_shader_reference(struct pipe_context *ctx,
                       struct util_live_shader_cache *cache,
                       void **dst, void *src);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif