Add a `fix' for another whitespace bug.

If the sentence starts with a multiple of eight spaces, the sentence
should in almost all practical cases have started with tabs instead.
Replace these spaces by tabs.

tools/tools/fixwhite/fixwhite.1

@@ -41,6 +41,8 @@ and prints the result to standard output.
 It removes leading and trailing empty lines from the input, as well as
 trailing whitespace characters from ever line of text.
 Multiple successive empty lines are merged together.
+If the whitespace at the beginning of a sentence is exactly a multiple
+of eight spaces, the whitespace is replaced by tabs.
 Also, spaces preceeding tabs will be merged into the tab character.
 .Sh AUTHORS
 .An Ed Schouten Aq ed@FreeBSD.org

tools/tools/fixwhite/fixwhite.c

@@ -110,6 +110,19 @@ savewhite(char c, bool leading)
 static void
 printwhite(void)
 {
+	off_t i;
+
+	/* Merge spaces at the start of a sentence to tabs if possible. */
+	if ((column % 8) == 0) {
+		for (i = 0; i < column; i++)
+			if (!peekbyte(i + 1, ' '))
+				break;
+		if (i == column) {
+			queuelen -= column;
+			for (i = 0; i < column; i += 8)
+				queue[queuelen++] = '\t';
+		}
+	}
 
 	if (fwrite(queue, 1, queuelen, stdout) != queuelen) {
 		perror("write");