fix generating syscall-names.h for loongarch64

fix generating syscall-names.h for loongarch64

The <bits/syscall.h> from musl loongarch64 arch contains some
indirect syscall definitions:
 #define __NR3264_fcntl                  25
 #define __NR_fcntl                      __NR3264_fcntl

This will result in incorrect contents generated by make_syscall_h_sh:
 [__NR3264_fcntl] = "fcntl",

To fix this issue, all macros staring with __NR3264_ should be also
copied to the generated syscall-names.h

Signed-off-by: Weijie Gao <[email protected]>