build: fix link error on some platforms. Fixes #5235

Some users may have libtool libs (.la) installed in their linker search paths.
In this case, using -static-libtool-libs would try to link in .a's instead of
shared libs. That would be harmless unless the .a was built in a way that
would break linking, like non-fpic.

What we really want is "-static" here. Despite its name, it's actually less
aggressive than -static-libtool-libs. It causes only internal libs to be linked
statically (libbitcoinconsensus is the one were'a after).