opengauss5.0+postgis2.4.2的安装小记
opengauss5.0软件安装：
参看：https://docs-opengauss.osinfra.cn/zh/docs/5.0.0/docs/InstallationGuide/%E8%8E%B7%E5%8F%96%E5%AE%89%E8%A3%85%E5%8C%85_%E4%BC%81%E4%B8%9A%E7%89%88.html
postgis安装：
postgis安装参考：（几个大坑注意）
https://docs-opengauss.osinfra.cn/zh/docs/5.0.0/docs/ExtensionReference/PostGIS%E5%AE%89%E8%A3%85.html
坑1：
编译报内存不够分配
as: error while loading shared libraries: libopcodes-2.27-44.base.el7_9.1.so: failed to map segment from shared object: Cannot allocate memory
