Remove RageFile::SeekCur(). It's just as easy to call Seek(Tell()), and

separating "seek from current position" doesn't do anything useful for
file drivers.

stepmania/src/RageFileDriverZip.cpp

@@ -285,7 +285,7 @@ void RageFileDriverZip::ParseZipfile()
 		if( got == 0 ) /* skip */
 			continue;
 
-		zip.SeekCur( info.extra_field_length );
+		zip.Seek( zip.Tell() + info.extra_field_length );
 
 		FileInfo *pInfo = new FileInfo(info);
 		Files.push_back( pInfo );

stepmania/src/RageSurface_Load_JPEG.cpp

@@ -109,7 +109,7 @@ void RageFile_JPEG_skip_input_data( j_decompress_ptr cinfo, long num_bytes )
 	num_bytes -= in_buffer;
 
 	if( num_bytes )
-		src->file->SeekCur( num_bytes );
+		src->file->Seek( src->file->Tell() + num_bytes );
 }
 
 void RageFile_JPEG_term_source( j_decompress_ptr cinfo )