package/minicom: fix musl build

Add two upstream patches to fix the build of minicom with the musl C
library.

Fixes:

  http://autobuild.buildroot.net/results/ea7/ea72a5aee30a89251c06e6a916499e39128437c0/



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
[Thomas: use upstream patches instead of OpenEmbedded patch.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>