ext/intl: fix build with older ICU

[oerdnj]

Covariant return types for clone() were only introduced in ICU 65; before that NumberFormat::clone() returns Format*, so cast the result explicitly in NumberFormatter_object_clone().

<unicode/numberrangeformatter.h> is a C++-only header, and older ICU does not wrap it in U_SHOW_CPLUSPLUS_API, so including it from php_intl.c breaks the C compile. Move it into the __cplusplus branch, next to the using declaration that needs it.

[oerdnj]

I know that Debian Buster is long dead, but this is a simple change and will help with the packaging for older releases.

[devnexen]

Covariant return types for clone() were only introduced in ICU 64; before that NumberFormat::clone() returns Format*, so cast the result explicitly in NumberFormatter_object_clone().

Are you sure it s not ICU 65 (NumberFormat::clone() as virtual) ?

[devnexen]

lgtm static_cast is safe to use in this case.

[oerdnj]

Covariant return types for clone() were only introduced in ICU 64; before that NumberFormat::clone() returns Format*, so cast the result explicitly in NumberFormatter_object_clone().

Are you sure it s not ICU 65 (NumberFormat::clone() as virtual) ?

Debian Buster had 63.1-6+deb10u4 and Debian Bullseye had 67.1-7, so it some version of ICU between these two versions. But reading the changelog, I think you might be right: https://icu.unicode.org/download/65

I've amended the commit and the comment above and force pushed.

[devnexen]

Thanks !