[thirdparty] add license info about yaml-cpp and chrony

Added license information on yaml-cpp and chrony (build/test-only
dependency) into thirdparty/LICENSE.txt.

This patch doesn't have any functional modifications.

Change-Id: I65dfaa917fdf4f0831471b3e730bf8be19ebdc2d
Reviewed-on: http://gerrit.cloudera.org:8080/14637
Tested-by: Kudu Jenkins
Reviewed-by: Alexey Serbin <[email protected]>
(cherry picked from commit 9e6e729)
Reviewed-on: http://gerrit.cloudera.org:8080/14645

thirdparty/LICENSE.txt

@@ -604,6 +604,31 @@ thirdparty/src/thrift-*/: Apache 2.0 license
 libraries: libthrift
 Source: https://thrift.apache.org
 
+--------------------------------------------------------------------------------
+thirdparty/src/yaml-cpp-yaml-cpp-*/: MIT license
+libraries: libyaml-cpp
+Source: https://github.com/jbeder/yaml-cpp
+
+Copyright (c) 2008-2015 Jesse Beder.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
 ================================================================================
 BUILD-ONLY DEPENDENCIES
 ================================================================================
@@ -659,3 +684,8 @@ NOTE: build-time dependency
 thirdparty/src/curl-*/: MIT/X derivative license
 Source: http://curl.haxx.se/
 NOTE: build-time dependency
+
+--------------------------------------------------------------------------------
+thirdparty/src/chrony-*/: GPLv2 license (https://www.gnu.org/licenses/gpl.html)
+Source: https://chrony.tuxfamily.org/
+NOTE: build-time dependency