Move TBB's global extensions dir.

The new place corresponds better to where Debian puts the Iceweasel
extensions. Also, it will allow us to drop the useless "Browser"
sub-dir in TBB_INSTALL without having potential collisions (e.g. if
there was a "Browser/extensions").

config/chroot_local-includes/usr/local/lib/tails-shell-library/tor-browser.sh

@@ -2,7 +2,7 @@
 
 TBB_INSTALL=/usr/local/lib/tor-browser
 TBB_PROFILE=/etc/tor-browser/profile
-TBB_EXT="${TBB_INSTALL}/extensions"
+TBB_EXT=/usr/local/share/tor-browser-extensions
 
 exec_firefox() {
     LD_LIBRARY_PATH="${TBB_INSTALL}"/Browser

config/chroot_local-includes/usr/local/sbin/i2p-browser

@@ -25,8 +25,8 @@ START_PAGE="http://127.0.0.1:7657"
 # Import the TBB_INSTALL, TBB_EXT and TBB_PROFILE variables
 . /usr/local/lib/tails-shell-library/tor-browser.sh
 
-NOSCRIPT="${TBB_INSTALL}/extensions/{73a6fe31-595d-460b-a920-fcc0f8843232}.xpi"
-TORBUTTON="${TBB_INSTALL}/extensions/torbutton@torproject.org"
+NOSCRIPT="${TBB_EXT}/{73a6fe31-595d-460b-a920-fcc0f8843232}.xpi"
+TORBUTTON="${TBB_EXT}/torbutton@torproject.org"
 NAME="`gettext \"I2P Browser\"`"
 
 if [ -e /var/lib/gdm3/tails.camouflage ]; then