icedove branding: adopting current Makefile.in style from upstream

To get the branding usable within multiple build directorys we need to
change the Makefile.in files to the current needs.
debian/rules: switching to debhelper

Adding the needed changes that comming by the switch to debhelper
as build system. Finally are more changes to the rules file needed.
debian/mozconfig*: adding mozconfig files

Adding various mozconfig files for building ID and it's corrosponding
debug binarys.
There is 'mozconfig.default' that includes the basic instructions for
all builds. This file is included later by any other mozconfig files to
use the variables there.
debian/icedove.configopts: file no longer needed

The configuration for the package(s) build is now held inside the mozconfig
files.
switching the old thunderbird*.in files to icedove.*

By removing the the applications name switch in the rules files the old
debian/*.in files are not needed any longer. We only building Icedove
related packages.
Depending on this we also don't need to take care about application
names in the menu or post and preinst scripts. Removing all old
substitutions variables inside the files.
debian/icedove.links: adding /u/b/i link

The CDBS creates the links while building, now just let debhelper doing
the linkage.
debian/icedove.dirs: adding helper file for needed directorys
debian/icedove.install: sort entrys alphabetical
debian/icedove.js: fix small typo and reformating
debian/rules: adding override for dh_fixperms
debian/rules: adding override for dh_install

calendar-google-provider and iceowl-extension needs special handling, we
repack the already created *.xpi files later. So we have to extract them
first.
Because of the branding we also have to install our own icons for the
Icedove grafics.
The icedove-dev package doesn't needs to ship the
lib{mozalloc,mozjs,xul}.so. We link them to the librarys which comes
with the standard icedove package. Removed for depulication.
debian/rules: adding override for dh_shlibdeps
debian/rules: correcting Icedove version inside icedove.pc while install
debian/rules: adding override for dh_strip

Without the additional argument for dh_strip the icedove-dbg package
isn't builded.
debian/control: remove ${shlibs:Depends} from c-g-p depends

dpkg-gencontrol remains a unknown substitution variable
${shlibs:Depends} for the calendar-google-provider package. It's not
needed so remove the Depends list.
debian/rules: adding additional LDFLAGS
remove this file, it's confusing git-pbuilder

   !!!! Do not pick this commit !!!!
fixing FTBFS hppa

Closes: #741245