xdiff/xemit.c (xdl_find_func): Elide trailing white space in a context header.

This removes trailing blanks from git-generated diff headers
the same way a similar patch did that for GNU diff:

  http://article.gmane.org/gmane.comp.gnu.utils.bugs/13839

That is, it removes trailing blanks on the hunk header line that
shows the function name.
Signed-off-by: NJim Meyering <jim@meyering.net>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

xdiff/xemit.c

@@ -90,7 +90,7 @@ static void xdl_find_func(xdfile_t *xf, long i, char *buf, long sz, long *ll) {
 		     *rec == '#')) {	/* #define? */
 			if (len > sz)
 				len = sz;
-			if (len && rec[len - 1] == '\n')
+			while (0 < len && isspace((unsigned char)rec[len - 1]))
 				len--;
 			memcpy(buf, rec, len);
 			*ll = len;