hw/9pfs: move G_GNUC_PRINTF to header

v9fs_path_sprintf() is annotated with G_GNUC_PRINTF(2, 3) in
hw/9pfs/9p.c, but the prototype in hw/9pfs/9p.h is missing the
attribute, so callers that include only the header do not get format
checking.

Move the annotation to the header and delete the duplicate in the
source file. No behavior change.

Signed-off-by: Sean Wei <me@sean.taipei>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250613.qemu.9p.02@sean.taipei>
[CS: fix code style (max. 80 chars per line)]
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>

hw/9pfs/9p.c

@@ -201,8 +201,7 @@ void v9fs_path_free(V9fsPath *path)
 }
 
 
-void G_GNUC_PRINTF(2, 3)
-v9fs_path_sprintf(V9fsPath *path, const char *fmt, ...)
+void v9fs_path_sprintf(V9fsPath *path, const char *fmt, ...)
 {
     va_list ap;
 

hw/9pfs/9p.h

@@ -456,7 +456,8 @@ static inline uint8_t v9fs_request_cancelled(V9fsPDU *pdu)
 void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu);
 void v9fs_path_init(V9fsPath *path);
 void v9fs_path_free(V9fsPath *path);
-void v9fs_path_sprintf(V9fsPath *path, const char *fmt, ...);
+void G_GNUC_PRINTF(2, 3) v9fs_path_sprintf(V9fsPath *path, const char *fmt,
+                                           ...);
 void v9fs_path_copy(V9fsPath *dst, const V9fsPath *src);
 size_t v9fs_readdir_response_size(V9fsString *name);
 int v9fs_name_to_path(V9fsState *s, V9fsPath *dirpath,