escapeshellarg documentation is missing the locale dependency

[jannisbaudisch]

The following paragraph should be added:

escapeshellarg() will strip all invalid characters according to your locale settings (e.g. latin-1 characters are stripped when locale/LC_CTYPE is UTF-8). Please keep in mind that the locale support depends on you C standard library while compiling. This might result in strange behavior on embedded systems.

[cmb69]

This is true for systems where mblen(3) is available (probably all systems); see also https://bugs.php.net/bug.php?id=80731.