Provide glibc-compatible SYS_* aliases for the __NR_* constants.

This helps us remove another external/strace bionic hack.

Change-Id: I3e82c0d2fd27e479be98f096e05b666fd16f8eb3
diff --git a/libc/include/sys/syscall.h b/libc/include/sys/syscall.h
index 7055518..a44b2e5 100644
--- a/libc/include/sys/syscall.h
+++ b/libc/include/sys/syscall.h
@@ -33,6 +33,8 @@
 #include <sys/types.h>
 #include <asm/unistd.h>
 
+#include <sys/glibc-syscalls.h> /* glibc-compatible SYS_* aliases for our __NR_* names. */
+
 __BEGIN_DECLS
 
 int syscall(int number, ...);