This commit adds three patches that are needed to fix build issues on
musl:
- <error.h> not available on musl
- structure redefinitions due to direct inclusion of kernel headers
- missing <sys/ttydefaults.h> inclusion
Patches have been submitted upstream:
http://lists.unix-ag.uni-kl.de/pipermail/vpnc-devel/2016-June/004186.html
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>