CMake: Improvements from kitware

• Add multiple CMake option to control which parts of CDI should be built
• Add installation of the cdilib and associated CMake config file
• Fix some issues with linking
• Fix some issues in cdi-config.cmake

CMakeLists.txt

@@ -7,7 +7,6 @@ set(CMAKE_C_STANDARD 11)
 include(CTest)
 include(CheckIncludeFile)
 
-
 # Finding libraries
 ### -------------- Pthread ---------------------------
 
@@ -17,6 +16,7 @@ if(${CDI_PTHREAD})
   find_package(Threads REQUIRED)
   set_target_properties(Threads::Threads PROPERTIES THREADS_PREFER_PTHREAD_FLAG TRUE)
   list(APPEND cdi_compile_defs HAVE_PTHREAD=1)
+  list(APPEND cdi_linked_libs pthread)
 endif()
 
 # enable default internal libs
@@ -45,7 +45,6 @@ if(${CDI_SERVICE})
   list(APPEND cdi_compile_defs HAVE_LIBSERVICE=1)
 endif()
 
-
 # ecCodes
 option(CDI_ECCODES "Use the eccodes library [default=ON]" ON)
 if(${CDI_ECCODES} OR eccodes_ROOT)
@@ -53,6 +52,7 @@ if(${CDI_ECCODES} OR eccodes_ROOT)
   if (${eccodes_FOUND})
     list(APPEND cdi_compile_defs HAVE_LIBGRIB_API=${eccodes_FOUND})
     message(VERBOSE "added compile definition HAVE_LIBGRIB_API=${eccodes_FOUND}")
+    list(APPEND cdi_linked_libs eccodes)
   else()
     message(WARNING "eccodes not found, compiling without eccodes")
   endif ()
@@ -70,6 +70,7 @@ if(${CDI_NETCDF} OR netCDF_ROOT )
       HAVE_LIBGRIB_API=${netCDF_FOUND}
       HAVE_LIBGRIB=${netCDF_FOUND}
     )
+    list(APPEND cdi_linked_libs netCDF::netcdf)
   else()
     message(WARNING "netcdf target not found, compiling without netcdf")
   endif ()
@@ -82,8 +83,13 @@ message(VERBOSE "looking for config.h in: ${PROJECT_BINARY_DIR}/src")
 list(APPEND cdi_compile_defs CDI=1 CDI_SIZE_TYPE=size_t PACKAGE_NAME="${PROJECT_NAME}" VERSION="${CMAKE_PROJECT_VERSION}")
 add_subdirectory(src)
 
-#tests
-add_subdirectory(app)
-add_subdirectory(tests)
-
+#app
+option(CDI_BUILD_APP "Build the app" ON)
+if (CDI_BUILD_APP)
+  add_subdirectory(app)
+endif ()
 
+#tests
+if (BUILD_TESTING)
+  add_subdirectory(tests)
+endif ()