FS_POSIX: handle Files.getFileStore() failures

Android unconditionally throws a SecurityException;[1] getFileStore()
is not supported. Catch the exception and don't attempt the hard-
linking atomic file mechanism.

[1] https://android.googlesource.com/platform/libcore/+/21e6175e25

Bug: 548947
Change-Id: Idfba2d9dbcbc80ea15ab2ae7889e5142444c1581
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

org.eclipse.jgit/src/org/eclipse/jgit/util/FS_POSIX.java

@@ -396,7 +396,12 @@ public class FS_POSIX extends FS {
 		}
 		Path lockPath = lock.toPath();
 		Path link = null;
-		FileStore store = Files.getFileStore(lockPath);
+		FileStore store = null;
+		try {
+			store = Files.getFileStore(lockPath);
+		} catch (SecurityException e) {
+			return true;
+		}
 		try {
 			Boolean canLink = CAN_HARD_LINK.computeIfAbsent(store,
 					s -> Boolean.TRUE);
@@ -462,7 +467,12 @@ public class FS_POSIX extends FS {
 		}
 		Path link = null;
 		Path path = file.toPath();
-		FileStore store = Files.getFileStore(path);
+		FileStore store = null;
+		try {
+			store = Files.getFileStore(path);
+		} catch (SecurityException e) {
+			return token(true, null);
+		}
 		try {
 			Boolean canLink = CAN_HARD_LINK.computeIfAbsent(store,
 					s -> Boolean.TRUE);