Explanation why --disable-rpath-hack is needed:
When building on pistachio_x86 $(LDFLAGS) contains '-L[...]/l4/lib'
which will be transformed by autoconf to '-rpath [...]/l4/lib'.
Now the problem at hand is that we pretend to be FreeBSD when we are
actually not. So autoconf assumes it is valid to use '-path' when it
is actually not.
Also we use zlib for (de)compressing gzipped streams/files instead of
calling gzip as this currently somewhat buggy.
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