package/readline: add Signed-off-by and renumber patch

Add Signed-off-by and while at it, renumber it

Fixes:
 - https://bugs.buildroot.org/show_bug.cgi?id=13731

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/readline/0001-curses-link.patch

@@ -3,6 +3,8 @@ link readline directly to ncurses since it needs symbols from it
 upstream readline does this on purpose (no direct linking), but
 it doesn't make much sense in a Linux world
 
+Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
+
 --- a/support/shobj-conf
 +++ b/support/shobj-conf
 @@ -42,7 +42,7 @@