Adding a cmake option to exclude the jsoncpp files from install. (#1596)

* Adding a cmake option to exclude the jsoncpp files from install. Useful when used used as a submodule

* Updaing help text

---------

Co-authored-by: Jordan Bayles <bayles.jordan@gmail.com>

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5ab9c52..4eb4499 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -79,6 +79,7 @@
 option(JSONCPP_WITH_PKGCONFIG_SUPPORT "Generate and install .pc files" ON)
 option(JSONCPP_WITH_CMAKE_PACKAGE "Generate and install cmake package files" ON)
 option(JSONCPP_WITH_EXAMPLE "Compile JsonCpp example" OFF)
+option(JSONCPP_WITH_INSTALL "Include JsonCpp header and binaries in the install target" ON)
 option(JSONCPP_STATIC_WINDOWS_RUNTIME "Use static (MT/MTd) Windows runtime" OFF)
 option(BUILD_SHARED_LIBS "Build jsoncpp_lib as a shared library." ON)
 option(BUILD_STATIC_LIBS "Build jsoncpp_lib as a static library." ON)

include/CMakeLists.txt

diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
index dc40d95..bbd6405 100644
--- a/include/CMakeLists.txt
+++ b/include/CMakeLists.txt
@@ -1,5 +1,8 @@
+if (JSONCPP_WITH_INSTALL)
+
 file(GLOB INCLUDE_FILES "json/*.h")
 install(FILES
     ${INCLUDE_FILES}
     DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/json)
 
+endif()
\ No newline at end of file

src/lib_json/CMakeLists.txt

diff --git a/src/lib_json/CMakeLists.txt b/src/lib_json/CMakeLists.txt
index 3037eb0..86722ac 100644
--- a/src/lib_json/CMakeLists.txt
+++ b/src/lib_json/CMakeLists.txt
@@ -196,6 +196,8 @@
     list(APPEND CMAKE_TARGETS ${OBJECT_LIB})
 endif()
 
+if (JSONCPP_WITH_INSTALL)
+
 install(TARGETS ${CMAKE_TARGETS} ${INSTALL_EXPORT}
     RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
     LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
@@ -203,3 +205,4 @@
     OBJECTS DESTINATION ${CMAKE_INSTALL_LIBDIR}
 )
 
+endif()