Fix procfs.c compilation

procfs.c doesn't currently compile on Solaris:

/vol/src/gnu/gdb/hg/master/dist/gdb/procfs.c: In member function ‘virtual int procfs_target::can_use_hw_breakpoint(bptype, int, int)’:
/vol/src/gnu/gdb/hg/master/dist/gdb/procfs.c:3017:9: error: ‘ptr_type’ was not declared in this scope; did you mean ‘var_types’?
 3017 |   type *ptr_type
      |         ^~~~~~~~
      |         var_types

This was caused by this patch:

commit 99d9c3b92ca96a7425cbb6b1bf453ede9477a2ee
Author: Simon Marchi <simon.marchi@efficios.com>
Date:   Fri Sep 29 14:24:38 2023 -0400

    gdb: remove target_gdbarch

Partially undoing it restores the build.

Tested on amd64-pc-solaris2.11.
1 file changed