Cygwin: testsuite: Tweak lseek03 after addition of SEEK_HOLE

After addition of SEEK_HOLE, the whence of *4* is not an invalid
argument, causing the test to FAIL.

See ltp commit  423e636a4c8f ("lseek03: change to fix with the lseek syscall")

winsup/testsuite/winsup.api/ltp/lseek03.c

@@ -129,7 +129,7 @@ char fname[255];
 int fd;
 int Rec_sigsys = 0;
 
-int Whences[] = { 4, -1, 7 };
+int Whences[] = { 5, -1, 7 };
 
 int
 main(int ac, char **av)