Add five new escape sequences to wscons

[Crystal Kolipe <kolipe.c%exoticsilicon.com@localhost>]

Here is a patch to implement five additional escape sequences in the wscons
vt100 emulation.

This is a port of some code that I originally wrote for OpenBSD, and which was
recently accepted into CVS there.

It's useful, because these sequences correspond to the terminfo capabilities
rin, indn, vpa, hpa, and cbt as defined in the xterm terminfo entry.  With
these sequences implemented, it becomes slightly more practical to set
TERM=xterm when connecting to remote systems that don't have a comprehensive
terminfo database.

The current lack of support for cbt, vpa, and hpa is actually mentioned in
the comments in the terminfo file, (see line 2533).

--- dev/wscons/wsemul_vt100_subr.c.dist	2018-12-05 22:42:20.000000000 -0300
+++ dev/wscons/wsemul_vt100_subr.c	2023-01-16 08:35:17.292084228 -0300
@@ -188,7 +188,7 @@
 void
 wsemul_vt100_handle_csi(struct vt100base_data *edp, u_char c)
 {
-	int n, help, flags, fgcol, bgcol;
+	int n, m, help, flags, fgcol, bgcol;
 	long attr, bkgdattr;
 
 #define A3(a, b, c) (((a) << 16) | ((b) << 8) | (c))
@@ -410,6 +410,9 @@
 		edp->ccol -= uimin(DEF1_ARG(edp, 0), edp->ccol);
 		edp->flags &= ~VTFL_LASTCHAR;
 		break;
+	    case 'G': /* CHA */
+		edp->ccol = uimin(DEF1_ARG(edp, 0)-1, edp->ncols-1);
+		break;
 	    case 'H': /* CUP */
 	    case 'f': /* HVP */
 		if (edp->flags & VTFL_DECOM)
@@ -445,15 +448,40 @@
 			COPYCOLS(edp, edp->ccol + n, edp->ccol, help);
 		ERASECOLS(edp, NCOLS(edp) - n, n, edp->bkgdattr);
 		break;
+	    case 'S': /* SU */
+		wsemul_vt100_scrollup (edp,DEF1_ARG(edp, 0));
+		break;
+	    case 'T': /* SD */
+		wsemul_vt100_scrolldown (edp,DEF1_ARG(edp, 0));
+		break;
 	    case 'X': /* ECH erase character */
 		n = uimin(DEF1_ARG(edp, 0), COLS_LEFT(edp) + 1);
 		ERASECOLS(edp, edp->ccol, n, edp->bkgdattr);
 		break;
+	    case 'Z': /* CBT */
+		if (edp->ccol == 0)
+			break;
+		for (m = 0; m < DEF1_ARG(edp, 0); m++) {
+			if (edp->tabs) {
+				for (n = edp->ccol - 1; n > 0; n--) {
+					if (edp->tabs[n])
+						break;
+				}
+			} else
+				n = (edp->ccol - 1) & ~7;
+			edp->ccol = n;
+			if (n == 0)
+				break;
+		}
+		break;
 	    case 'c': /* DA primary */
 		if (ARG(edp, 0) == 0)
 			wsdisplay_emulinput(edp->cbcookie, WSEMUL_VT_ID1,
 					    sizeof(WSEMUL_VT_ID1));
 		break;
+	    case 'd': /* VPA */
+		edp->crow = uimin(DEF1_ARG(edp, 0)-1, edp->nrows-1);
+ 		break;
 	    case 'g': /* TBC */
 		KASSERT(edp->tabs != 0);
 		switch (ARG(edp, 0)) {