Re-enable sys tests on cpp (#8424)

* [skip travis] re-enable sys tests on cpp

* [skip travis] disable args tests on cpp Windows

tests/runci/targets/Cpp.hx

@@ -64,11 +64,9 @@ class Cpp {
 				}
 		}
 
-		if (ci != AppVeyor) { // #8280
-			changeDirectory(sysDir);
-			runCommand("haxe", ["compile-cpp.hxml"]);
-			runCpp("bin/cpp/Main-debug", []);
-		}
+		changeDirectory(sysDir);
+		runCommand("haxe", ["compile-cpp.hxml"]);
+		runCpp("bin/cpp/Main-debug", []);
 
 		changeDirectory(threadsDir);
 		runCommand("haxe", ["build.hxml", "-cpp", "export/cpp"]);

tests/sys/src/TestUnicode.hx

@@ -334,7 +334,7 @@ class TestUnicode extends utest.Test {
 
 		// args
 		#if !cs // C# behaves like Windows here
-		if (#if (java || eval || hl) Sys.systemName() != "Windows" #else true #end) {
+		if (#if (java || eval || hl || cpp) Sys.systemName() != "Windows" #else true #end) {
 			// https://stackoverflow.com/questions/7660651/passing-command-line-unicode-argument-to-java-code
 			UnicodeSequences.normalBoth(str -> {
 					assertUEquals(runUtility(["args", str]).stdout, str + endLine);