LTP tip busted for x86_64 + glibc !

@@ -22,7 +22,7 @@
 #include "linux_syscall_numbers.h"
 
 #if !defined(HAVE_PREADV)
-int preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset)
+ssize_t preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset)
 {
        return tst_syscall(__NR_preadv, fd, iov, iovcnt, offset);
 }

@@ -22,7 +22,7 @@
 #include "linux_syscall_numbers.h"
 
 #if !defined(HAVE_PWRITEV)
-int pwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset)
+ssize_t pwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset)
 {
        return tst_syscall(__NR_pwritev, fd, iov, iovcnt, offset);