编译安装nginx需要pcre包，未安装会有如下提示：
./configure: error: the HTTP rewrite module requires the PCRE library.
You can either disable the module by using --without-http_rewrite_module
option, or install the PCRE library into the system, or build the PCRE library
statically from the source with nginx by using --with-pcre=<path> option.
需要安装pcre的devel包，pcre-devel。使用yum安装即可：（以下命令还带有ssl、zlib等依赖的安装）
yum -y install zlib zlib-devel openssl openssl--devel pcre pcre-devel
