This constant can be handy for tools like PIE to determine the origin of a PHP
binary to provide better output / diagnostics.
see php/pie#275
see php/php-src#18168
When global constants' or class constants' availability is based on some
preprocessor condition, the generated arginfo header files wrap the
declarations in the preprocessor `#if` conditional blocks, one per declaration,
even if they are in the same conditional block based on comments in the stub
file. Instead of having multiple conditional blocks one after the other with
the same condition, combine them into a single conditional block.
This information can be occasionally useful, and would otherwise need
to be parsed from `phpinfo()` output.
However, maybe more importantly we unify the build date between what is
given by `php -v` and `php -i`, since these compilation units are not
necessarily preprocessed within the same second.
Closes GH-16747.
The PHP_SBINDIR symbol was defined on *nix systems but never used. This
adds the constant similar to PHP_BINDIR also to PHP. On Windows it is
the value of prefix configuration when PHP was built (same value as
PHP_BINDIR).
Basically all constants are now declared via stubs. The rest of the constants are either deprecated (`SID` or `MHASH_*`) or out of interest (`__COMPILER_HALT_OFFSET__` and `PHP_CLI_PROCESS_TITLE`).
