inkscape: Fix build on NixOS

The first problem that was introduced in a276d516
was a linking error:

ld: cannot find -licui18n
ld: cannot find -licuuc
ld: cannot find -licudata

So I added icu to the buildInputs.

The second problem was that the interpreter wasn't patched in
share/filters, apparently this is only needed when building with
autotools:

make[3]: Entering directory '/build/inkscape-0.92.3/share/filters'
./i18n.py ./filters.svg > ./filters.svg.h
./i18n.py: /usr/bin/env: bad interpreter: No such file or directory

A similar error also occurs for share/palettes, share/patterns,
share/symbols and share/templates, so I added patching the interpreter
there as well.

Switching to autotools in Inkscape is a very bad idea, because upstream
currently still has their own autotools files in the 0.92.x tree but
master already has them removed, see this commit:

https://gitlab.com/inkscape/inkscape/commit/e471a664f923f517b68071f2e33fbb6ce070f8b7



However for the sake of trying to not break Inkscape on Darwin again,
I tried to keep the fixes minimal and not went back to CMake.

I did however mark the stuff that's unneeded for CMake, so that we can
avoid forgetting to remove that crap once we get back to CMake.

Signed-off-by: aszlig <aszlig@nix.build>
Cc: @matthewbauer