Removed test dir 4 which was doing the same thing as the other test dir number 4.

test cases/csharp/4 pkgconfig/meson.build

@@ -1,12 +0,0 @@
-project('C# pkg-config', 'cs')
-
-nunit_dep = dependency('nunit', required : false)
-
-if not nunit_dep.found()
-  error('MESON_SKIP_TEST nunit not found.')
-endif
-
-nunit_runner = find_program('nunit-console')
-
-test_lib = library('test_lib', 'test-lib.cs', dependencies: nunit_dep)
-test('nunit test', nunit_runner, args: test_lib)

test cases/csharp/4 pkgconfig/test-lib.cs

@@ -1,11 +0,0 @@
-using NUnit.Framework;
-
-[TestFixture]
-public class NUnitTest
-{
-    [Test]
-    public void Test() 
-    {
-        Assert.AreEqual(1 + 1, 2);
-    }
-}