Commit 4e7064d173 removed the usage of
`aclocal.m4`. When using Git repositories, many times cleaning of the
generated files is not done prior to running phpize or buildconf. For
example:
git clone git://github.com/php/php-src
cd php-src
git checkout PHP-7.3
./buildconf
./configure
git checkout PHP-7.4
./buildconf # -> warnings
./configure # -> errors
To not accidentally include `aclocal.m4` file in the generated configure
this enhances build system experience a bit more by removing aclocal.m4
file prior to start building configure file using phpize or buildconf.
f9db357623