package/pulseaudio: remove WebRTC hook for toolchains without C++

package/pulseaudio: remove WebRTC hook for toolchains without C++

This hook is not required anymore since we handle WebRTC dependency
with --enable/disable-webrtc-aec.

Also the hook doesn't have any effect since we use autoreconf because
it should have been a POST_CONFIGURE_HOOKS.

So, we can remove it safely.

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Cc: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>