Libtool will yell at you if you try to link a shared library against
static ones.
This change creates a libtool archive library for bitcoincrypto and
allows a shared library to be linked against it portably.
Also specify -static in both:
- ..._la_CXXFLAGS so that libtool will avoid building two versions of
each object (one PIC, one non-PIC). We just need the one that is
suitable for static linking.
- ..._la_LDFLAGS so that libtool will create a static library.
[META] This change is done in preparation for a future commit where we
link the libbitcoinkernel library against this one.
c1e16cb31f