./configure --with-php7 fails silently

Apparently there is a php 7.4 configuration missing.  This is bindings 
1.4.17 running on a Mint 20 system.

I see this in the config output:

cpython-38.opt-1.pyc
checking for php-config7.3... no
checking for php-config7.2... no
checking for php-config7.1... no
checking for php-config7.0... no
checking for php-config... no

It didn't look for 7.4.

Thanks,

Jim.