Fix make install

vendor/cxxopts/CMakeLists.txt

@@ -1,15 +1,15 @@
 # Copyright (c) 2014 Jarryd Beck
-# 
+#
 # 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
@@ -36,7 +36,7 @@ enable_testing()
 
 option(CXXOPTS_BUILD_EXAMPLES "Set to ON to build examples" ON)
 option(CXXOPTS_BUILD_TESTS "Set to ON to build tests" ON)
-option(CXXOPTS_ENABLE_INSTALL "Generate the install target" ON)
+option(CXXOPTS_ENABLE_INSTALL "Generate the install target" OFF)
 
 # request c++11 without gnu extension for the whole project and enable more warnings
 if (CXXOPTS_CXX_STANDARD)