[improvement]: pjsip: Upgrade bundled version to pjproject 2.16

[silentindark]

Improvement Description

Upgrade Asterisk to bundled pjproject 2.16

More information: https://github.com/pjsip/pjproject/releases/tag/2.16

Pull request to third-party asterisk/third-party#20

[silentindark]

At compile time got

In file included from /usr/src/asterisk-20.17.0/third-party/pjproject/source/pjlib/include/pj/assert.h:51, from /usr/src/asterisk-20.17.0/third-party/pjproject/source/pjsip/include/pjsip/sip_uri.h:29, from /usr/src/asterisk-20.17.0/third-party/pjproject/source/pjsip/include/pjsip.h:27, from res_hep_pjsip.c:37: /usr/src/asterisk-20.17.0/third-party/pjproject/source/pjlib/include/pj/os.h:267:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes] 267 | PJ_DECL(pj_status_t) pj_thread_unregister(); | ^~~~~~~

Looks like that is related with this PR https://github.com/pjsip/pjproject/pull/4626 that introduced new APIs.

[silentindark]

These warnings can be fixed by adding this change to pj/os.h:

`--- a/pjlib/include/pj/os.h.orig 2025-11-26 02:00:05.000000000 +0200 +++ b/pjlib/include/pj/os.h 2025-12-02 11:54:53.132903235 +0200 @@ -264,7 +264,7 @@ *

• @return PJ_SUCCESS on success. */ -PJ_DECL(pj_status_t) pj_thread_unregister(); +PJ_DECL(pj_status_t) pj_thread_unregister(void);

/**

• Register a thread that was created by external or native API to PJLIB.`