Update t_program.h

In constructor Allocating memory by calling "new t_scope". 
Assigning: "this->scope_" = "new t_scope". 
The constructor allocates field "scope_" of "t_program" but there is no destructor in the code.
destructor should deallocate memroy for scope_. 
which sometimes causes Resource Leak.
To resolve the issue added destructor and released the scope_