@PcodeUserop
		@EmuSyscall("syscall0")
		public byte[] test_syscall0(byte[] arg0, byte[] arg1, byte[] arg2, byte[] arg3) {
			return arg3;
		}
A library with two 4-argument syscalls.

<p>
For x86:LE:64:default:gcc, the storage for the 4th argument varies by calling convention. For
__stdcall, it's RCX. For syscall, it's R10. Both syscalls just return the 4th argument. Thus,
it's possible to detect whether the emulator heeds conventions by binding each to a different
convention, then invoking them with distinct values placed in RCX and R10 and verifying that
the correct value shows in RAX, the return register.
Ghidra/Features/SystemEmulation/src/test/java/ghidra/pcode/emu/sys/EmuAmd64SyscallUseropLibraryTest.java