MT#62181 timer: provide copy constructor

This makes it possible to retain the previously set absolute expiry
time. Update trans_timer to use this (the only relevant place).

Change-Id: I9765fbeddd2807406d2603b3c7fd9e8c9c09db68

core/sip/sip_trans.h

@@ -97,7 +97,7 @@ public:
     {}
 
     trans_timer(const trans_timer& ti, int bucket_id, sip_trans* t)
-        : timer(ti.expires), type(ti.type),
+        : timer(ti), type(ti.type),
 	  bucket_id(bucket_id), t(t)
     {}
 

core/sip/wheeltimer.h

@@ -70,6 +70,11 @@ public:
 	  prev(0), expires(0), expires_rel(expires)
     {}
 
+    timer(const timer &t)
+        : base_timer(),
+	  prev(0), expires(t.expires), expires_rel(t.expires_rel)
+    {}
+
     ~timer(); 
 
     virtual void fire()=0;