Fix #79026: Allow PHP_EXTRA_VERSION overrides

When building from sources, someone distributing PHP may want to add a
vendor specific string to the PHP_VERSION so users can differentiate
multiple vendor builds from the same PHP version. For instance, a vendor
backporting a bug fix to a no-longer-supported PHP version could extend
their PHP_EXTRA_VERSION to allow their users to identify that they carry
such fix by checking their PHP_VERSION.

Author: athos-ribeiro

configure.ac

@@ -64,7 +64,9 @@ IFS=$ac_IFS
 PHP_MAJOR_VERSION=[$]1
 PHP_MINOR_VERSION=[$]2
 PHP_RELEASE_VERSION=[$]3
-PHP_EXTRA_VERSION=[$]4
+dnl Allow overriding PHP_EXTRA_VERSION through the homonymous env var
+AC_ARG_VAR([PHP_EXTRA_VERSION], [Extra PHP version label suffix, e.g. '-dev', 'rc1', '-acme'])dnl
+AS_IF([test -z "$PHP_EXTRA_VERSION"],[PHP_EXTRA_VERSION=[$]4])
 PHP_VERSION="$PHP_MAJOR_VERSION.$PHP_MINOR_VERSION.$PHP_RELEASE_VERSION$PHP_EXTRA_VERSION"
 PHP_VERSION_ID=`expr [$]PHP_MAJOR_VERSION \* 10000 + [$]PHP_MINOR_VERSION \* 100 + [$]PHP_RELEASE_VERSION`