PROJ/m4/ax_check_compile_flag.m4, branch 8.1.1

PROJ/m4/ax_check_compile_flag.m4, branch 8.1.1 Forked from https://github.com/OSGeo/PROJ Add ax_check_compile_flag.m4 from 2018-03-18T03:37:30+00:00 Charles Karney charles@karney.com 2018-03-18T03:37:30+00:00 6978bd29ce1e6ced6cdc224dbbff9ed7fe3dcb05 https://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html

https://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html