implement ConfigureOp#check_lib

spec/build_tests_spec.rb

@@ -1699,6 +1699,32 @@ EOF
       end
     end
 
+    context "check_lib" do
+      it "succeeds when the requested library is found" do
+        test_dir "configure"
+        result = run_rscons(rsconsfile: "check_lib_success.rb", op: "configure")
+        expect(result.stderr).to eq ""
+        expect(result.status).to eq 0
+        expect(result.stdout).to match /Checking for library 'm'... found/
+      end
+
+      it "fails when the requested library is not found" do
+        test_dir "configure"
+        result = run_rscons(rsconsfile: "check_lib_failure.rb", op: "configure")
+        expect(result.stderr).to eq ""
+        expect(result.status).to_not eq 0
+        expect(result.stdout).to match /Checking for library 'mfoofoo'... not found/
+      end
+
+      it "succeeds when the requested library is not found but :fail is set to false" do
+        test_dir "configure"
+        result = run_rscons(rsconsfile: "check_lib_no_fail.rb", op: "configure")
+        expect(result.stderr).to eq ""
+        expect(result.status).to eq 0
+        expect(result.stdout).to match /Checking for library 'mfoofoo'... not found/
+      end
+    end
+
     context "check_executable" do
       it "succeeds when the requested executable is found" do
         test_dir "configure"