The USR modem isn't so bad that it needs parity generated

We just need to strip the high bit on RX because the mode leaves
it on received bytes.

src/syncterm/modem.c

@@ -15,13 +15,7 @@
 #include "uifcinit.h"
 
 static COM_HANDLE com = COM_HANDLE_INVALID;
-static pthread_once_t ptable_once = PTHREAD_ONCE_INIT;
-static char ptable[128];
-static int nbits[16] = {
-	0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4
-};
 static bool seven_bits = false;
-static int parity = SYNCTERM_PARITY_NONE;
 
 void
 modem_input_thread(void *args)
@@ -89,16 +83,6 @@ modem_output_thread(void *args)
 			if (seven_bits) {
 				for (i = 0; i < wr; i++)
 					conn_api.wr_buf[i] &= 0x7f;
-				switch (parity) {
-					case SYNCTERM_PARITY_NONE:
-						break;
-					case SYNCTERM_PARITY_EVEN:
-						conn_api.wr_buf[i] = ptable[conn_api.wr_buf[i]];
-						break;
-					case SYNCTERM_PARITY_ODD:
-						conn_api.wr_buf[i] = ptable[conn_api.wr_buf[i]] ^ 0x80;
-						break;
-				}
 			}
 			sent = 0;
 			while (com != COM_HANDLE_INVALID && sent < wr) {
@@ -164,26 +148,12 @@ modem_response(char *str, size_t maxlen, int timeout)
 	return 0;
 }
 
-void
-init_ptable(void)
-{
-	int i;
-	int nb;
-
-	for (i = 0; i < (sizeof(ptable) / sizeof(ptable[0])); i++) {
-		nb = nbits[i & 0x0f] | nbits[i >> 4];
-		ptable[i] = ((nb & 1) << 7) | i;
-	}
-}
-
 int
 modem_connect(struct bbslist *bbs)
 {
 	int  ret;
 	char respbuf[1024];
 
-	pthread_once(&ptable_once, init_ptable);
-	parity = bbs->parity;
 	seven_bits = (bbs->data_bits == 7);
 
 	if (!bbs->hidepopups)