docs: use SPDX license names

Let's use standardized names for licenses. The names used by SPDX
makes things more obvious at first glance. For complete list see:
https://spdx.org/licenses/

Note, this commit does not change any license or so...

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

README.licensing

@@ -2,19 +2,21 @@
 The project util-linux doesn't use the same license for all of the code.
 There is code under:
 
-   * GPLv2+ (GNU General Public License version 2, or any later version)
+   * GPL-2.0-or-later   - GNU General Public License version 2, or any later version
 
-   * GPLv2 (GNU General Public License version 2)
+   * GPL-2.0            - GNU General Public License version 2
 
-   * LGPLv2+ (GNU Lesser General Public License v2 (or 2.1) or any later version)
+   * LGPL-2.1-or-later  - GNU Lesser General Public License 2.1 or any later version
 
-   * BSD with advertising
+   * BSD-3-Clause       - BSD 3-Clause "New" or "Revised" License
+
+   * BSD-4-Clause-UC    - BSD 4-Clause University of California-Specific
 
    * Public Domain
 
 Please, check the source code for more details. A license is usually at the start
 of each source file.
 
-The ./COPYING file (GPLv2+) is the default license for code without an explicitly
-defined license.
+The ./COPYING file (GPL-2.0-or-later) is the default license for code without
+an explicitly defined license.
 

libblkid/COPYING

@@ -5,4 +5,4 @@ version 2.1 of the License, or (at your option) any later
 version.
 
 The complete text of the license is available in the
-../Documentation/licenses/COPYING.LGPLv2.1 file.
+../Documentation/licenses/COPYING.LGPL-2.1-or-later file.

libfdisk/COPYING

@@ -5,4 +5,4 @@ version 2.1 of the License, or (at your option) any later
 version.
 
 The complete text of the license is available in the
-../Documentation/licenses/COPYING.LGPLv2.1 file.
+../Documentation/licenses/COPYING.LGPL-2.1-or-later file.

libmount/COPYING

@@ -5,4 +5,4 @@ version 2.1 of the License, or (at your option) any later
 version.
 
 The complete text of the license is available in the
-../Documentation/licenses/COPYING.LGPLv2.1 file.
+../Documentation/licenses/COPYING.LGPL-2.1-or-later

libsmartcols/COPYING

@@ -5,4 +5,4 @@ version 2.1 of the License, or (at your option) any later
 version.
 
 The complete text of the license is available in the
-../Documentation/licenses/COPYING.LGPLv2.1 file.
+../Documentation/licenses/COPYING.LGPL-2.1-or-later file.

libuuid/COPYING

@@ -2,4 +2,4 @@ This library is free software; you can redistribute it and/or
 modify it under the terms of the Modified BSD License.
 
 The complete text of the license is available in the
-../Documentation/licenses/COPYING.BSD-3 file.
+../Documentation/licenses/COPYING.BSD-3-Clause file.