Side effect ? autogen can not be built with autoconf-2.69d on Solaris 11.3 x86/x64.

Hello,
Autogen-5.18.16 can not be built with autoconf-2.69d.
It was possible with autoconf 2.69.


$ uname -a
SunOS hidden 5.11 11.3 i86pc i386 i86pc Solaris

$ gcc --version
gcc (GCC) 10.2.0

Autoconf-2.69d is installed without error.
$ ./configure --prefix=/opt/local CC=gcc CXX=g++
$ make
$ make -k check
  :
## ------------- ##
## Test results. ##
## ------------- ##

488 tests behaved as expected.
54 tests were skipped.

$ make install

$ autoconf --version
autoconf (GNU Autoconf) 2.69d


But, autogen-5.18.16 can not be built, which was possible with autoconf 2.69.
$ cd /tmp/autogen-5.18.16 
$ ./configure --prefix=/opt/local CC=gcc CXX=g++
  :
config.status: executing depfiles commands
config.status: error: in `/tmp/autogen-5.18.16':
config.status: error: Something went wrong bootstrapping makefile fragments
    for automatic dependency tracking.  Try re-running configure with the
    '--disable-dependency-tracking' option to at least be able to build
    the package (albeit without support for automatic dependency tracking).
See `config.log' for more details

$ ./configure --disable-dependency-tracking --prefix=/opt/local CC=gcc CXX=g++
  :
checking for runetype.h... no
checking for wchar.h... yes
configure: error: you must have stdlib.h on your system


Regards,