Suppress "Unlikely argument type for equals()" warnings in tests

This new warning was introduced in Eclipse 4.7 Oxygen [1].

The only instances of the warning are in test code that is asserting
that some class does not compare equal to Strings. As in the Gerrit
project [2] these asserts are arguably overkill, but arguably also
a reasonable test of an equals implementation. Ignore the warning in
these cases.

Note that if the project is opened in an earlier version of Eclipse,
a warning "Unsupported @SuppressWarnings" will be emitted.

[1] https://www.eclipse.org/eclipse/news/4.7/M6/
[2] https://gerrit-review.googlesource.com/#/c/gerrit/+/110339/

Change-Id: I08ea33d71e6009cf0f37e6492a475931f447256b
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit.lfs.test/tst/org/eclipse/jgit/lfs/lib/AbbreviatedLongObjectIdTest.java

@@ -587,6 +587,7 @@ public void testGetFirstByte() {
 		assertEquals(id.getFirstByte(), a.getFirstByte());
 	}
 
+	@SuppressWarnings("unlikely-arg-type")
 	@Test
 	public void testNotEquals() {
 		AbbreviatedLongObjectId a = new LongObjectId(1L, 2L, 3L, 4L)

org.eclipse.jgit.test/tst/org/eclipse/jgit/diff/EditListTest.java

@@ -53,6 +53,7 @@
 import org.junit.Test;
 
 public class EditListTest {
+	@SuppressWarnings("unlikely-arg-type")
 	@Test
 	public void testEmpty() {
 		final EditList l = new EditList();

org.eclipse.jgit.test/tst/org/eclipse/jgit/diff/EditTest.java

@@ -125,6 +125,7 @@ public void testToString() {
 		assertEquals("REPLACE(1-2,1-4)", e.toString());
 	}
 
+	@SuppressWarnings("unlikely-arg-type")
 	@Test
 	public void testEquals1() {
 		final Edit e1 = new Edit(1, 2, 3, 4);

org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevObjectTest.java

@@ -60,6 +60,7 @@ public void testId() throws Exception {
 		assertSame(a, a.getId());
 	}
 
+	@SuppressWarnings("unlikely-arg-type")
 	@Test
 	public void testEquals() throws Exception {
 		final RevCommit a1 = commit();