libpcscspy.c: do not use pcsc_stringify_error()

Fix the library loading by dlopen(), for example with OpenSC.

$ LIBPCSCLITE_DELEGATE=/lib/x86_64-linux-gnu/libpcscspy.so.0 opensc-tool -a
loading "/lib/x86_64-linux-gnu/libpcscspy.so.0" failed: /lib/x86_64-linux-gnu/libpcscspy.so.0: undefined symbol: pcsc_stringify_error
No smart card readers found.
Failed to connect to reader: No readers found

src/spy/libpcscspy.c

@@ -205,8 +205,8 @@ static void spy_quit(const char *fname, LONG rv)
  struct timeval profile_time;
 
  gettimeofday(&profile_time, NULL);
- spy_line("<|%ld|%ld|%s|%s|0x%08lX", profile_time.tv_sec,
- profile_time.tv_usec, fname, pcsc_stringify_error(rv), rv);
+ spy_line("<|%ld|%ld|%s|0x%08lX", profile_time.tv_sec,
+ profile_time.tv_usec, fname, rv);
 }
 
 #define Enter() spy_enter(__FUNCTION__)