Fix pread/pwrite for LP64.

Unlike on 32-bit systems where off_t is 32-bit, we don't want to
throw away the top 32 bits of an LP64 system's 64-bit off_t.

Change-Id: Ib2e0daeb4fc0b8ab3d1b983d0b371d8f81033b50
diff --git a/libc/arch-aarch64/syscalls/pread64.S b/libc/arch-aarch64/syscalls/pread64.S
index 82a2fb2..941e55f 100644
--- a/libc/arch-aarch64/syscalls/pread64.S
+++ b/libc/arch-aarch64/syscalls/pread64.S
@@ -21,3 +21,6 @@
 
     ret
 END(pread64)
+
+    .globl _C_LABEL(pread)
+    .equ _C_LABEL(pread), _C_LABEL(pread64)