[CMake] Fix installation of llvm-ranlib on multiconfig builder.

Introduce install_symlink.cmake from clang/tools/driver/clang_symlink.cmake.

FIXME: Would it be generalized?
llvm-svn: 223655

llvm/tools/llvm-ar/CMakeLists.txt

@@ -24,4 +24,4 @@ add_custom_command(OUTPUT ${llvm_ranlib}
                    DEPENDS llvm-ar)
 
 add_custom_target(llvm-ranlib ALL DEPENDS ${llvm_ranlib})
-install(FILES "${llvm_ranlib}" DESTINATION bin)
+install(SCRIPT install_symlink.cmake -DCMAKE_INSTALL_PREFIX=\"${CMAKE_INSTALL_PREFIX}\")

llvm/tools/llvm-ar/install_symlink.cmake

@@ -0,0 +1,25 @@
+# We need to execute this script at installation time because the
+# DESTDIR environment variable may be unset at configuration time.
+# See PR8397.
+
+if(UNIX)
+  set(LINK_OR_COPY create_symlink)
+  set(DESTDIR $ENV{DESTDIR})
+else()
+  set(LINK_OR_COPY copy)
+endif()
+
+# CMAKE_EXECUTABLE_SUFFIX is undefined on cmake scripts. See PR9286.
+if( WIN32 )
+  set(EXECUTABLE_SUFFIX ".exe")
+else()
+  set(EXECUTABLE_SUFFIX "")
+endif()
+
+set(bindir "${DESTDIR}${CMAKE_INSTALL_PREFIX}/bin/")
+
+message("Creating llvm-ranlib")
+
+execute_process(
+  COMMAND "${CMAKE_COMMAND}" -E ${LINK_OR_COPY} "llvm-ar${EXECUTABLE_SUFFIX}" "llvm-ranlib${EXECUTABLE_SUFFIX}"
+  WORKING_DIRECTORY "${bindir}")