Fix procfs.c compilation on Solaris

procfs.c doesn't compile on trunk and the gdb-18 branch:

procfs.c: In function ‘int procfs_notice_thread(procinfo*, procinfo*, void*)’:
procfs.c:2857:33: error: invalid use of non-static member function ‘thread_state thread_info::state() const’
 2857 |   if (thr == NULL || thr->state == THREAD_EXITED)
      |                      ~~~~~~~~~~~^~~~~~~~~~~~~~~~

Fixed by calling the member function.

procfs.c: In function ‘bool find_memory_regions_callback(prmap*, find_memory_region_ftype)’:
procfs.c:3152:15: error: no match for call to ‘(find_memory_region_ftype {aka gdb::function_view<bool(long unsigned int, long unsigned int, bool, bool, bool, bool, bool, bool)>}) (CORE_ADDR, std::size_t&, bool, bool, bool, bool, bool)’
 3152 |   return func ((CORE_ADDR) map->pr_vaddr,
      |          ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
 3153 |                map->pr_size,
      |                ~~~~~~~~~~~~~
 3154 |                (map->pr_mflags & MA_READ) != 0,
      |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 3155 |                (map->pr_mflags & MA_WRITE) != 0,
      |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 3156 |                (map->pr_mflags & MA_EXEC) != 0,
      |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 3157 |                true, /* MODIFIED is unknown, pass it as true.  */
      |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 3158 |                false);
      |                ~~~~~~

Fixed by passing the new HOLE arg.

procfs.c: In function ‘void info_proc_mappings(procinfo*, int)’:
procfs.c:3257:25: error: too many arguments to function ‘bool iterate_over_mappings(procinfo*, find_memory_region_ftype, bool (*)(prmap*, find_memory_region_ftype))’
 3257 |   iterate_over_mappings (pi, NULL, NULL, info_mappings_callback);
      |   ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixed by removing the unused arg.

Tested on sparcv9-sun-solaris2.11 and amd64-pc-solaris2.11 with results
similar to the gdb-17 ones.