Use a pkg-config wrapper during cross-compilation.

This prevents the build system from trying to use headers and libraries
on the host machine when building for a different architecture.
flac: Use configure flags instead of *FLAGS variables.

This prevents configure from adding -L/lib/ to OGG_LIBS, which breaks
the build on ARM.
Restart rdnssd service (which includes dhcp6c and radvd) when ntp updates time to proper value for the first time
Stop dhcp6c before starting in case it was already running
Do not start radvd when dhcp6c is stopping
Do not restart radvd if it is already running
openvpn: updated to 2.3.4
Merge pull request #613 from pinwing/ipv6

Restart rdnssd service when ntp updates time to proper value for the first time
Merge pull request #611 from ppuryear/pkg-config

Use a pkg-config wrapper during cross-compilation.
Merge pull request #612 from ppuryear/fix-flac-build

flac: Use configure flags instead of *FLAGS variables.
build: Added more parallelization to the build process
Merge branch 'master' of github.com:RMerl/asuswrt-merlin
Don't make the led_control() call for the RT-AC68U LED_5G re-apply led behaviour to the controler, as it causes erratic blinking behaviour - the watchdog periodically calls led_control() to make the 5G LED blink through software.

Now we only write to gpio on a led_control(LED_5G, state) call, and have a separate constant called LED_5G_FORCED which will actually setup the led behaviour register.

Made Stealth Mode use the new constant.
Updated documentation
Missing from previous commit
Merge branch 'master' of github.com:RMerl/asuswrt-merlin
Properly re-enable all LEDs when coming out of Stealth Mode with an RT-AC56
Updated documentation
Merge pull request #616 from pinwing/radvd

Do not restart radvd if it is already running
Merge pull request #615 from pinwing/dhcp6c

Do not start radvd when dhcp6c is stopping
rstats: Initialize a few vars to ensure we don't end up working with random values