Remove unused sys_pread64 and sys_pwrite64 parsers on Linux

* io.c [HAVE_LONG_LONG_OFF_T]: Remove sys_pread64 and sys_pwrite64
aliases.
(sys_pread64, sys_pwrite64): Define these functions only on
[SVR4 && _LFS64_LARGEFILE] platform.
* linux/mips/syscallent.h: Use sys_pread and sys_pwrite to handle
appropriate syscalls.
* linux/syscall.h (sys_pread64, sys_pwrite64): Remove.
* syscall.c (dumpio): Check sys_pread64 and sys_pwrite64 only on
[SVR4 && _LFS64_LARGEFILE] platform.
diff --git a/syscall.c b/syscall.c
index 2575317..eaf0f45 100644
--- a/syscall.c
+++ b/syscall.c
@@ -2303,7 +2303,11 @@
 	if (qual_flags[tcp->u_arg[0]] & QUAL_READ) {
 		if (sysent[tcp->scno].sys_func == sys_read ||
 		    sysent[tcp->scno].sys_func == sys_pread ||
+#ifdef SVR4
+#if _LFS64_LARGEFILE
 		    sysent[tcp->scno].sys_func == sys_pread64 ||
+#endif
+#endif
 		    sysent[tcp->scno].sys_func == sys_recv ||
 		    sysent[tcp->scno].sys_func == sys_recvfrom)
 			dumpstr(tcp, tcp->u_arg[1], tcp->u_rval);
@@ -2314,7 +2318,11 @@
 	if (qual_flags[tcp->u_arg[0]] & QUAL_WRITE) {
 		if (sysent[tcp->scno].sys_func == sys_write ||
 		    sysent[tcp->scno].sys_func == sys_pwrite ||
+#ifdef SVR4
+#if _LFS64_LARGEFILE
 		    sysent[tcp->scno].sys_func == sys_pwrite64 ||
+#endif
+#endif
 		    sysent[tcp->scno].sys_func == sys_send ||
 		    sysent[tcp->scno].sys_func == sys_sendto)
 			dumpstr(tcp, tcp->u_arg[1], tcp->u_arg[2]);