replace malloc macros in imports.h with u_memory.h versions

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3024>

src/mesa/main/shared.c

@@ -43,6 +43,7 @@
 
 #include "util/hash_table.h"
 #include "util/set.h"
+#include "util/u_memory.h"
 
 static void
 free_shared_state(struct gl_context *ctx, struct gl_shared_state *shared);