kernel: add KERNEL_FTRACE_SYSCALLS option

Newer kernels propose to trace system calls, add an option to allow just
that.

Signed-off-by: Florian Fainelli <florian@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@37146 3c298f89-4303-0410-b956-a3cf2f4a3e73
odhcp6c: add missing config parameter

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@37148 3c298f89-4303-0410-b956-a3cf2f4a3e73
odhcp6c: avoid integer overflows in resend logic

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@37150 3c298f89-4303-0410-b956-a3cf2f4a3e73
scripts/feeds: ensure that --ff is enabled

Users may have merge.ff set to false, which will force merge commits to
be generated.  The intent here is to have a fast-forward merge when
possible, so let's make sure fast-forwards are enabled.

Signed-off-by: John Szakmeister <john@szakmeister.net>