This commit log Scilab version at ./configure to ease maintenance. It
uses Scilab include next to the bin directory which will work for both
system-wide install and binaries from scilab.org.
SCILAB_VERSION is define as an automake variable for easier
failure investigation.
Note: the Ubuntu Scilab version is used when available, in the current
CI config there is:
* Scilab 5.5 from scilab.org
* Scilab 6.0 from Ubuntu 18.04
* Scilab 6.1 from Ubuntu 20.04
The ubuntu-20.04 machine has php 7.4 and 8.0 installed.
configure.ac always looks for newer versions over older versions of php.
To prevent always testing 8.0, remove all versions and just install the
required version.
It is not available out of the box in GitHub environment, unlike under
Travis CI, so install it ourselves.
Note that we do it manually because installing the rael-gc/rvm PPA
doesn't seem to work with weird failures in GitHub Actions environment.
We also can't use gpg2 --recv-keys in this environment as it doesn't
work, apparently due to a firewall.
