Merge branch 'js/format-2047' into maint

Various rfc2047 quoting issues around a non-ASCII name on the From:
line in the output from format-patch have been corrected.

* js/format-2047:
  format-patch tests: check quoting/encoding in To: and Cc: headers
  format-patch: fix rfc2047 address encoding with respect to rfc822 specials
  format-patch: make rfc2047 encoding more strict
  format-patch: introduce helper function last_line_length()
  format-patch: do not wrap rfc2047 encoded headers too late
  format-patch: do not wrap non-rfc2047 headers too early
  utf8: fix off-by-one wrapping of text

utf8.c

@@ -353,7 +353,7 @@ retry:
 
 		c = *text;
 		if (!c || isspace(c)) {
-			if (w < width || !space) {
+			if (w <= width || !space) {
 				const char *start = bol;
 				if (!c && text == start)
 					return w;