text: let indenting/commenting skip the last line if its x is zero

If the marked region ends at the start of a line, do not include that
line in the indenting/undenting or commenting/uncommenting.  This is
closer to what the eye would expect.

src/proto.h

@@ -609,6 +609,8 @@ void remove_magicline(void);
 #ifndef NANO_TINY
 void mark_order(const filestruct **top, size_t *top_x, const filestruct
 	**bot, size_t *bot_x, bool *right_side_up);
+void get_region(const filestruct **top, size_t *top_x,
+        const filestruct **bot, size_t *bot_x);
 #endif
 size_t get_totsize(const filestruct *begin, const filestruct *end);
 #ifndef NANO_TINY

src/text.c

@@ -300,8 +300,8 @@ void do_indent(void)
 
     /* Use either all the marked lines or just the current line. */
     if (openfile->mark)
-	mark_order((const filestruct **)&top, &top_x,
-			(const filestruct **)&bot, &bot_x, NULL);
+	get_region((const filestruct **)&top, &top_x,
+			(const filestruct **)&bot, &bot_x);
     else {
 	top = openfile->current;
 	bot = top;
@@ -405,8 +405,8 @@ void do_unindent(void)
 
     /* Use either all the marked lines or just the current line. */
     if (openfile->mark)
-	mark_order((const filestruct **)&top, &top_x,
-			(const filestruct **)&bot, &bot_x, NULL);
+	get_region((const filestruct **)&top, &top_x,
+			(const filestruct **)&bot, &bot_x);
     else {
 	top = openfile->current;
 	bot = top;
@@ -509,8 +509,8 @@ void do_comment(void)
 
     /* Determine which lines to work on. */
     if (openfile->mark)
-	mark_order((const filestruct **)&top, &top_x,
-			(const filestruct **)&bot, &bot_x, NULL);
+	get_region((const filestruct **)&top, &top_x,
+			(const filestruct **)&bot, &bot_x);
     else {
 	top = openfile->current;
 	bot = top;

src/utils.c

@@ -532,6 +532,17 @@ void mark_order(const filestruct **top, size_t *top_x, const filestruct
     }
 }
 
+/* Get the start and end points of the marked region, but
+ * push the end point back if it's at the start of a line. */
+void get_region(const filestruct **top, size_t *top_x,
+	const filestruct **bot, size_t *bot_x)
+{
+    mark_order(top, top_x, bot, bot_x, NULL);
+
+    if (*bot_x == 0)
+	*bot = (*bot)->prev;
+}
+
 /* Given a line number, return a pointer to the corresponding struct. */
 filestruct *fsfromline(ssize_t lineno)
 {