[gfortran, patch] PR libfortran/21950

[François-Xavier Coudert]

Committed on mainline. For 4.0, I can't regenerate configure:

$ autoconf
configure.ac:71: error: possibly undefined macro: TL_AC_GCC_VERSION
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.
$ autoconf --version
autoconf (GNU Autoconf) 2.59

Did I miss something in the magic incantations? ("autoheader && autoconf")