gdb/fortran: clean-up Fortran intrinsic types

gdb/fortran: clean-up Fortran intrinsic types

The currently implemented intrinsic type handling for Fortran missed some
tokens and their parsing.  While still not all Fortran type kinds are
implemented this patch at least makes the currently handled types
consistent.  As an example for what this patch does, consider the
intrinsic type INTEGER.  GDB implemented the handling of the
keywords "integer" and "integer_2" but missed "integer_4" and "integer_8"
even though their corresponding internal types were already available as
the Fortran builtin types builtin_integer and builtin_integer_s8.
Similar problems applied to LOGICAL, REAL, and COMPLEX.  This patch adds
all missing tokens and their parsing.  Whenever a section containing the
type handling was touched, it also was reordered to be in a more easy to
grasp order.  All INTEGER/REAL/LOGICAL/COMPLEX types were grouped
together and ordered ascending in their size making a missing one more
easy to spot.

Before this change GDB would print the following when tyring to use the
INTEGER keywords:

   (gdb) set language fortran
   (gdb) ptype integer*1
   unsupported kind 1 for type integer
   (gdb) ptype integer_1
   No symbol table is loaded.  Use the "file" command.
   (gdb) ptype integer*2
   type = integer*2
   (gdb) ptype integer_2
   type = integer*2
   (gdb) ptype integer*4
   type = integer
   (gdb) ptype integer_4
   No symbol table is loaded.  Use the "file" command.
   (gdb) ptype integer*8
   type = integer*8
   (gdb) ptype integer_8
   No symbol table is loaded.  Use the "file" command.
   (gdb) ptype integer
   type = integer

With this patch all keywords are available and the GDB prints:

   (gdb) set language fortran
   (gdb) ptype integer*1
   type = integer*1
   (gdb) ptype integer_1
   type = integer*1
   (gdb) ptype integer*2
   type = integer*2
   (gdb) ptype integer_2
   type = integer*2
   (gdb) ptype integer*4
   type = integer*4
   (gdb) ptype integer_4
   type = integer*4
   (gdb) ptype integer*8
   type = integer*8
   (gdb) ptype integer_8
   type = integer*8
   (gdb) ptype integer
   type = integer

The described changes have been applied to INTEGER, REAL, COMPLEX,
and LOGICAL. Existing testcases have been adapted to reflect the
new behavior.  Tests for formerly missing types have been added.