only define msync cancellation point if the syscall exists

libpthread/linuxthreads.old/wrapsyscall.c

@@ -96,9 +96,11 @@ CANCELABLE_SYSCALL (off64_t, lseek64, (int fd, off64_t offset, int whence),
 		    (fd, offset, whence))
 #endif
 
+#ifdef __NR_msync
 /* msync(2).  */
 CANCELABLE_SYSCALL (int, msync, (__ptr_t addr, size_t length, int flags),
 		    (addr, length, flags))
+#endif
 
 
 /* nanosleep(2).  */