Update to webkit-gtk-2.4.3 and properly (try) to handle --disable-gtk-doc.

XXX: still NOT READY, but if you are adventurous please continue reading...

Please note that now I am able to complete the build phase on
NetBSD/i386 6.1.4. I have also updated PLIST but I still did not installed it
due various errors with HTML_DIR.
I removed all invasive changes to GNUMakefile* (patch-al) and configure
(patch-configure) regarding --enable-gtk-doc* and added to our Makefile.common
"--disable-gtk-doc-html".

I hope that I will be finally able to install it... My build will (hopefully)
finish on Sunday evening/night (GMT+1). :)

PS: please note that you will need >=~2GB of RAM and swap during the install
phase... In this machine I have 767MB of RAM and 1GB of swap but it is not
sufficient for linking with ld(1) in the install phase... Creating a 1GB swap
file solved this issue (thank you asau@):

 # dd if=/dev/zero of=/swap bs=1m count=1000
 # chmod 600 /swap
 # swapctl -a -p 1 /swap