examples: License the examples under a permissive BSD license.

See also:
https://lists.fedoraproject.org/archives/list/legal@lists.fedoraproject.org/thread/JR53JW52OKOL2S6O27NMNMO5SIM356X6/
https://bugzilla.redhat.com/show_bug.cgi?id=1713767

COPYING.LIB

@@ -1,3 +1,9 @@
+This is the general license covering libnbd.  The example code (in the
+examples/ subdirectory) is distributed under a different license, see
+examples/LICENSE-FOR-EXAMPLES.
+
+----------------------------------------------------------------------
+
                   GNU LESSER GENERAL PUBLIC LICENSE
                        Version 2.1, February 1999
 

examples/LICENSE-FOR-EXAMPLES

@@ -0,0 +1,38 @@
+The files in the examples/ directory are licensed under this very
+permissive BSD license.  This means that you can copy, use, adapt and
+modify them without any significant restrictions.  You can also
+combine them with proprietary code or include them in code that is
+distributed under other open source licenses.
+
+----------------------------------------------------------------------
+
+libnbd examples
+Copyright (C) 2013-2019 Red Hat Inc.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+* Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+* Neither the name of Red Hat nor the names of its contributors may be
+used to endorse or promote products derived from this software without
+specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGE.

examples/Makefile.am

@@ -17,6 +17,8 @@
 
 include $(top_srcdir)/subdir-rules.mk
 
+EXTRA_DIST = LICENSE-FOR-EXAMPLES
+
 noinst_PROGRAMS = \
 	batched-read-write \
 	simple-fetch-first-sector \

examples/batched-read-write.c

@@ -1,7 +1,4 @@
-/* This example can be copied, used and modified for any purpose
- * without restrictions.
- *
- * Example usage with nbdkit:
+/* Example usage with nbdkit:
  *
  * nbdkit -U - --filter=noparallel memory 2M \
  *   --run './batched-read-write $unixsocket'

examples/simple-fetch-first-sector.c

@@ -1,7 +1,4 @@
-/* This example can be copied, used and modified for any purpose
- * without restrictions.
- *
- * Example usage with nbdkit:
+/* Example usage with nbdkit:
  *
  * nbdkit -U - pattern 1M --run './simple-fetch-first-sector $unixsocket sector'
  *

examples/simple-reads-and-writes.c

@@ -1,7 +1,4 @@
-/* This example can be copied, used and modified for any purpose
- * without restrictions.
- *
- * Example usage with nbdkit:
+/* Example usage with nbdkit:
  *
  * nbdkit -U - memory 1M --run './simple-reads-and-writes $unixsocket'
  *

examples/threaded-reads-and-writes.c

@@ -1,7 +1,4 @@
-/* This example can be copied, used and modified for any purpose
- * without restrictions.
- *
- * Example usage with nbdkit:
+/* Example usage with nbdkit:
  *
  * nbdkit -U - memory 1M --run './threaded-reads-and-writes $unixsocket'
  *