Quote PHP_BINARY and CRUNZ_BIN in closure shell commands

[eyupcanakman]

Q	A
Fixed tickets	#109

On Windows, when PHP is installed under a path that contains spaces (e.g.
C:\Program Files\PHP\php.exe), closure-based tasks fail silently.
serializeClosure() in Event.php concatenates PHP_BINARY and CRUNZ_BIN
directly into the shell command string without quoting, so the OS splits the
path at the first space and tries to execute a truncated binary name.

Both values are now wrapped with escapeshellarg(), which adds the appropriate
quoting on every platform. The existing serializeClosure test is updated to
expect the quoted form.

[PabloKowalczyk]

Thanks @eyupcanakman, since it's a bug fix please target 3.9 branch

[eyupcanakman]

Rebased onto 3.9, thanks.

[PabloKowalczyk]

Thanks @eyupcanakman