Fixes:
 CVE-2016-2315
 CVE-2016-2324

Signed-off-by: Peter Wagner <tripolar@gmx.at>

Signed-off-by: Peter Wagner <tripolar@gmx.at>

Signed-off-by: Luka Perkov <luka@openwrt.org>

Signed-off-by: Peter Wagner <tripolar@gmx.at>

Previously, ./configure was running checking local system and not
OpenWRT target. This would avoid any configure test about OpenWRT
libraries.

With a patch in configure, non cross-compiling-friend test are
ignored and Makefile can use default configure.

As side effect, git commands are now at /usr/lib/git-core and not
/usr/libexec/git-core.

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>