remove fdfs_bulk_import from compile targets

INSTALL changed

Merge pull request #769 from khanhkhanhlele/client/fdfs_file_info.c

docs: fix typos in client/fdfs_file_info.c

set chg_count.trunk_server more gracefully

replace sprintf(buff, "%.2f", xxx) with fc_ftoa

INSTALL changed for v6.13.0

upgrade version to 6.12.4

upgrade version to 6.12.3

adapt to libserverframe 1.2.5

remove compile warnings