CMakeLists: use standard install directory variables

Use the variables provided by cmake for install directories to
standardize across build systems.

The hard-coded /lib appended to exec_prefix does not necessarily match
automake's $(libdir) (especially in multilib scenarios), so depending on
whether you're using cmake or automake, you could actually end up with
different pkg-config files given the right configuration, in addition to
files being installed in different directories.

Author: bkylerussell

CMakeLists.txt

@@ -69,6 +69,7 @@ include(CTest)
 #include("${CppUTestRootDirectory}/cmake/Modules/CheckFunctionExists.cmake")
 include("${CppUTestRootDirectory}/cmake/Modules/CppUTestBuildTimeDiscoverTests.cmake")
 include("${CppUTestRootDirectory}/cmake/Modules/CppUTestNormalizeTestOutputLocation.cmake")
+include(GNUInstallDirs)
 
 configure_file (
     "${PROJECT_SOURCE_DIR}/config.h.cmake"
@@ -91,8 +92,8 @@ if (TESTS)
     endif (EXTENSIONS)
 endif (TESTS)
 
-set (INCLUDE_INSTALL_DIR "include")
-set (LIB_INSTALL_DIR "lib")
+set (INCLUDE_INSTALL_DIR "${CMAKE_INSTALL_INCLUDEDIR}")
+set (LIB_INSTALL_DIR "${CMAKE_INSTALL_LIBDIR}")
 set (INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/include")
 
 # Pkg-config file.

src/CppUTest/CMakeLists.txt

@@ -68,6 +68,5 @@ endif (WIN32)
 install(FILES ${CppUTest_headers} DESTINATION include/CppUTest)
 install(TARGETS CppUTest
     EXPORT CppUTestTargets
-    RUNTIME DESTINATION bin
-    LIBRARY DESTINATION lib
-    ARCHIVE DESTINATION lib)
+    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})

src/CppUTestExt/CMakeLists.txt

@@ -43,6 +43,5 @@ target_link_libraries(CppUTestExt ${CPPUNIT_EXTERNAL_LIBRARIES})
 install(FILES ${CppUTestExt_headers} DESTINATION include/CppUTestExt)
 install(TARGETS CppUTestExt
     EXPORT CppUTestTargets
-    RUNTIME DESTINATION bin
-    LIBRARY DESTINATION lib
-    ARCHIVE DESTINATION lib)
+    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})