libsysprof-profile: add recording helper to capture file data

We might have the file data from the peer and can specify the data in the
capture writer directly.

It may be useful to allow compressing these too, but we can deal with that
at a later time.

src/libsysprof-profile/sysprof-recording-private.h

@@ -37,5 +37,9 @@ SysprofSpawnable     *_sysprof_recording_get_spawnable (SysprofRecording      *s
 DexFuture            *_sysprof_recording_add_file      (SysprofRecording      *self,
                                                         const char            *path,
                                                         gboolean               compress);
+void                  _sysprof_recording_add_file_data (SysprofRecording      *self,
+                                                        const char            *path,
+                                                        const char            *contents,
+                                                        gssize                 length);
 
 G_END_DECLS