libblkid: Don't keep reading same sector of ISO

We were reading the same sector over and over again when parsing ISO9660.
This patches fixes it.
libblkid: Expose more ISO9660 headers

In order to kill libosinfo's infamous udev rule[1], we need to make blkid
report the following information as udev properties on IS09660 media so
that libosinfo can make use of that for detection:

1. Volume ID (already exposed as label).
2. System ID.
3. Publisher ID.
4. Application ID.
5. Boot record's boot system ID, (almost always 'EL TORITO
   SPECIFICATION' if boot record is present).

Example use:

$ blkid -p -o udev Fedora-17-x86_64-DVD.iso
ID_FS_SYSTEM_ID=LINUX
ID_FS_APPLICATION_ID=GENISOIMAGE ISO 9660/HFS FILESYSTEM CREATOR (C)
1993 E.YOUNGDALE
ID_FS_UUID=2012-05-22-20-55-32-00
ID_FS_UUID_ENC=2012-05-22-20-55-32-00
ID_FS_BOOT_SYSTEM_ID=EL TORITO SPECIFICATION
ID_FS_LABEL=Fedora_17_x86_64
ID_FS_LABEL_ENC=Fedora\x2017\x20x86_64
ID_FS_TYPE=iso9660
ID_PART_TABLE_TYPE=dos

[1] https://fedorahosted.org/libosinfo/ticket/1

[kzak@redhat.com: - add blkid_ltrim_whitespace() and use it together
                    with blkid_rtrim_whitespace() to trim white spaces
                  - enlarge blkid values to 128 bytes
                  - add generic blkid_probe_set_id_label() function
                  - always terminate all _ID with \0
                  - don't export the _IDs to blkid cache]

Signed-off-by: Karel Zak <kzak@redhat.com>
libblkid: Probe UDF volumes for ISO9660 info as well

I have seen blkid failing to report any meaningful data on some of UDF
volumes I have (Windows installer media):

$ ./blkid -p -o udev en_windows_7_professional_with_sp1_x64_dvd_u_676939.iso
ID_FS_LABEL=UDF_Volume
ID_FS_LABEL_ENC=UDF\x20Volume
ID_FS_TYPE=udf

Also, once my patches to expose more of ISO9660 info get merged, we'd
also need the same info to be exposed for UDF volumes.

This patch adds ISO9660 probing to UDF volumes and here is the result I
see on my example UDF volume (together with my pending patch to expose
more ISO9660 information):

$ ./blkid -p -o udev en_windows_7_professional_with_sp1_x64_dvd_u_676939.iso
ID_FS_PUBLISHER_ID=MICROSOFT CORPORATION
ID_FS_APPLICATION_ID=CDIMAGE 2.54 (01/01/2005 TM)
ID_FS_UUID=2011-04-12-02-38-58-00
ID_FS_UUID_ENC=2011-04-12-02-38-58-00
ID_FS_BOOT_SYSTEM_ID=EL TORITO SPECIFICATION
ID_FS_LABEL=GSP1RMCPRXFRER_EN_DVD
ID_FS_LABEL_ENC=GSP1RMCPRXFRER_EN_DVD
ID_FS_TYPE=iso9660

$ ./blkid -p -o udev en_windows_xp_professional_with_service_pack_3_x86_cd_x14-80428.iso
ID_FS_PUBLISHER_ID=MICROSOFT CORPORATION
ID_FS_APPLICATION_ID=CDIMAGE 2.52 (03/09/2004 TM)
ID_FS_UUID=2008-04-14-12-00-00-00
ID_FS_UUID_ENC=2008-04-14-12-00-00-00
ID_FS_BOOT_SYSTEM_ID=EL TORITO SPECIFICATION
ID_FS_LABEL=GRTMPFPP_EN
ID_FS_LABEL_ENC=GRTMPFPP_EN
ID_FS_TYPE=iso9660

Before anyone asks, Yes! The UDF media I have is all legal and downloaded
directly from MSDN. :)

[kzak@redhat.com: - read LABEL from UDF only if not found anything
                    useful in ISO9660]

Signed-off-by: Karel Zak <kzak@redhat.com>
libblkid: read whole buffer for iso_volume_descriptor

Signed-off-by: Karel Zak <kzak@redhat.com>