Fortran, typeprint: Forward level of details to be printed for pointers.

Variable "show" was hardcoded to zero for pointer and reference types.
This implementation didn't allow a correct "whatis" print
for those types and results in same output for "ptype" and "whatis".

Before:
(gdb) whatis t3p
type = PTR TO -> ( Type t3
    integer(kind=4) :: t3_i
    Type t2 :: t2_n
End Type t3 )

After:
(gdb) whatis t3p
type = PTR TO -> ( Type t3 )

2016-05-25  Bernhard Heckel  <bernhard.heckel@intel.com>

gdb/Changelog:
	* f-typeprint.c (f_type_print_base): Replace 0 by show.

gdb/testsuite/Changelog:
	* gdb.fortran/type.f90: Add pointer variable.
	* gdb.fortran/whatis_type.exp: Add whatis/ptype of pointers.