package/mutt: fix build without makedoc

package/mutt: fix build without makedoc

Cross-compilation of mutt is broken since bump to version 1.13.3 with
commit d42603b3872a0eed5a5a3dda13843fb5835f15a5

Indeed, since upstream commit 9bacbaa9, even with --disable-doc, mutt
tries to generate and install documentation files.
Build fails because mutt wants to generate muttrc.man by building (and
then running) a makedoc binary with the target cross-compiler (which
will obviously fail).

See https://gitlab.com/muttmua/mutt/issues/202

To fix this issue, retrieve two upstream patches.

Fixes:
 - http://autobuild.buildroot.org/results/2b01b7e65c0dc0e1191ba48e02e31503958d82fe

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