Fix mkpart linux-swap bug: would use 0x83 rather than 0x82

Fix mkpart linux-swap bug: would use 0x83 rather than 0x82

* libparted/labels/bsd.c (bsd_partition_set_system): Include "misc.h".
Use is_linux_swap to test whether the type string matches.
* libparted/labels/dasd.c (dasd_read, dasd_partition_set_system): Likewise.
* libparted/labels/dos.c (msdos_partition_set_system): Likewise.
* libparted/labels/mac.c (mac_partition_set_system): Likewise.
* libparted/labels/rdb.c (amiga_partition_set_system): Likewise.
* libparted/labels/sun.c (sun_partition_set_system): Likewise.
Based on a patch by Kenneth MacDonald, from
<http://lists.gnu.org/archive/html/bug-parted/2007-07/msg00012.html>.
* libparted/labels/misc.h (is_linux_swap): New function/file.
* libparted/labels/Makefile.am (liblabels_la_SOURCES): Add misc.h.
* tests/t2100-mkswap.sh: New file, test for the above fix.
* tests/Makefile.am (TESTS): Add t2100-mkswap.sh.