Add CMake installation rules (#2184)

Add installation rules for all the binary targets.

Targets are installed under `<CMAKE_INSTALL_PREFIX>/bin/<CONFIG>` where
`<CONFIG>` is `CMAKE_BUILD_TYPE` for single-config generators, e.g. Unix
Makefiles and Ninja, or the build configuration for multi-config
generators, e.g. Ninja Multi-Config and Visual Studio.

This creates the target `install` on Unix and `INSTALL` on Windows.

test_conformance/compiler/CMakeLists.txt

@@ -31,3 +31,10 @@ add_custom_command(
         COMMAND ${CMAKE_COMMAND} -E copy_directory
         ${CLConform_SOURCE_DIR}/test_conformance/compiler/secondIncludeTestDirectory
         ${COMPILER_TEST_RESOURCES}/secondIncludeTestDirectory)
+
+include(GNUInstallDirs)
+
+install(DIRECTORY
+            ${CLConform_SOURCE_DIR}/test_conformance/compiler/includeTestDirectory
+            ${CLConform_SOURCE_DIR}/test_conformance/compiler/secondIncludeTestDirectory
+        DESTINATION ${CMAKE_INSTALL_BINDIR}/$<CONFIG>)