Add an optional alias list to SYSCALLS.TXT

This patch adds an optional alias list to SYSCALLS.TXT.  It is used to
create aliases for a syscall.  For x86-64, lseek64 is an alias for lseek.

Change-Id: Icb11fd2bb461ea4f5f0a26bfc585471d7d7cc468
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Pavel Chupin <pavel.v.chupin@intel.com>
diff --git a/libc/arch-x86_64/syscalls/lseek.S b/libc/arch-x86_64/syscalls/lseek.S
index 9756315..a237f8b 100644
--- a/libc/arch-x86_64/syscalls/lseek.S
+++ b/libc/arch-x86_64/syscalls/lseek.S
@@ -15,3 +15,6 @@
 1:
     ret
 END(lseek)
+
+    .globl _C_LABEL(lseek64)
+    .equ _C_LABEL(lseek64), _C_LABEL(lseek)