CPS: Support importing link_libraries

Teach CPS import to read the `link_libraries` attribute. We've exported
this for a long time, but apparently the code to read it back was never
implemented. (To be fair, use of this attribute is discouraged.)

Source/cmPackageInfoReader.cxx

@@ -801,6 +801,10 @@ void cmPackageInfoReader::SetTargetProperties(
                          configuration, NormalizeTargetName(dep, package));
   }
 
+  for (std::string const& lib : ReadList(data, "link_libraries")) {
+    AppendProperty(makefile, target, "LINK_LIBRARIES"_s, configuration, lib);
+  }
+
   // TODO: Handle non-configuration modules
   // once IMPORTED_CXX_MODULES supports it
   if (!configuration.empty()) {

Tests/FindPackageCpsTest/CMakeLists.txt

@@ -225,6 +225,10 @@ target_link_libraries(requires-test RequiresTest::Indirect)
 add_executable(requires-test-compile_only requires-test.cxx)
 target_link_libraries(requires-test-compile_only RequiresTest::CompileOnly)
 
+expect_property(
+  RequiresTest::Other INTERFACE_LINK_LIBRARIES
+  "link libraries" "every-config;$<$<CONFIG:test>:test-config>")
+
 expect_property(
   RequiresTest::Other IMPORTED_LINK_DEPENDENT_LIBRARIES
   "dyld requirements (any config)" "RequiresTest::Private1")

Tests/FindPackageCpsTest/cps/RequiresTest.cps

@@ -36,9 +36,11 @@
     },
     "Other": {
       "type": "dylib",
+      "link_libraries": [ "every-config" ],
       "dyld_requires": [ ":Private1" ],
       "configurations": {
         "test": {
+          "link_libraries": [ "test-config" ],
           "dyld_requires": [ ":Private2" ]
         }
       }