Unbreak databases/php73-mysqli when lang/php73 is build with MYSQLND=off

Currently when building lang/php73 with MYSQLND=off, its im possible to
build databases/php73-mysqli. When the option MYSQLND was added, we expected
users to not use mysqli at all after disabling this option.
This has proven to be wrong, so we patch the build to be work again.

patch-ext_mysqli_mysqli__api.c was submitted by Сергей <joker@pinnet.ru>.

Merge patches from r522478 into this commit and add two additional patches.