common.docker: Optimize image size building "ninja" in existing RUN command
common.docker: Optimize image size building "ninja" in existing RUN command

dockcross/dockcross,thewtex/cross-compilers,dockcross/dockcross,thewtex/cross-compilers,dockcross/dockcross,dockcross/dockcross,thewtex/cross-compilers,thewtex/cross-compilers