IVGCVSW-4488 Adding cxxopts to third-party

 * as alternative for boost::program_options
 * added to cmake
 * added to TPIP list in readme.md

Signed-off-by: Jan Eilers <jan.eilers@arm.com>
Change-Id: Id8c6a12c988196cdac55650bc4761c08a39b3abb
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3a15cec..91c6472 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -553,6 +553,7 @@
     src/profiling/backends/BackendProfiling.cpp
     src/profiling/backends/BackendProfiling.hpp
     third-party/half/half.hpp
+    third-party/cxxopts/cxxopts.hpp
     )
 
 # Files used for Streamline-based profiling backend