Add a new interface, sqlite3_context_db_handle(), that returns the database

connection pointer for an application-defined function. (CVS 4889)

FossilOrigin-Name: 54c55cae556af5a16c0ce8be1a96d2932db80ad8

src/vdbeapi.c

@@ -413,6 +413,15 @@ void *sqlite3_user_data(sqlite3_context *p){
   return p->pFunc->pUserData;
 }
 
+/*
+** Extract the user data from a sqlite3_context structure and return a
+** pointer to it.
+*/
+sqlite3 *sqlite3_context_db_handle(sqlite3_context *p){
+  assert( p && p->pFunc );
+  return p->s.db;
+}
+
 /*
 ** The following is the implementation of an SQL function that always
 ** fails with an error message stating that the function is used in the