Fixing gridfs_file_set_xxx wouldn’t export to module map.

When using clang to export modules, functions set of
mongo_gridfs_file_set_xxx couldn’t export to destination simply because
only the getting methods were marked with BSON_API. Typical scenario is
a third party exporting, such as c library exporting for Swift
language.
Script test-libmongoc, which includes GridFS, passed.
This issue was found by Kyle Jessup and Rockford Wei,
perfect.org

Author: RockfordWei

src/mongoc/mongoc-gridfs-file.h

@@ -28,23 +28,20 @@
 BSON_BEGIN_DECLS
 
 
-#define MONGOC_GRIDFS_FILE_STR_HEADER(name) \
-   BSON_API \
-   const char * \
-   mongoc_gridfs_file_get_##name (mongoc_gridfs_file_t * file); \
-   void \
-      mongoc_gridfs_file_set_##name (mongoc_gridfs_file_t * file, \
-                                     const char           *str);
-
-
-#define MONGOC_GRIDFS_FILE_BSON_HEADER(name) \
-   BSON_API \
-   const bson_t * \
-   mongoc_gridfs_file_get_##name (mongoc_gridfs_file_t * file); \
-   void \
-      mongoc_gridfs_file_set_##name (mongoc_gridfs_file_t * file, \
-                                     const bson_t * bson);
-
+#define MONGOC_GRIDFS_FILE_STR_HEADER(name)                                \
+   BSON_API                                                                \
+   const char *mongoc_gridfs_file_get_##name (mongoc_gridfs_file_t *file); \
+   BSON_API                                                                \
+   void mongoc_gridfs_file_set_##name (mongoc_gridfs_file_t *file,         \
+                                       const char *str);
+
+
+#define MONGOC_GRIDFS_FILE_BSON_HEADER(name)                                 \
+   BSON_API                                                                  \
+   const bson_t *mongoc_gridfs_file_get_##name (mongoc_gridfs_file_t *file); \
+   BSON_API                                                                  \
+   void mongoc_gridfs_file_set_##name (mongoc_gridfs_file_t *file,           \
+                                       const bson_t *bson);
 
 typedef struct _mongoc_gridfs_file_t mongoc_gridfs_file_t;
 typedef struct _mongoc_gridfs_file_opt_t mongoc_gridfs_file_opt_t;