buildroot

lbase64: compile with -fPIC

Some architectures (e.g. x86_64, MIPS, microblaze, or1k) require to
build with -fPIC to build a shared library, but the lbase64 build
system doesn't add it. Therefore, we add it in CFLAGS.

Fixes:
http://autobuild.buildroot.net/results/b56/b567096cbfdb89b1895924051265c56204ffb512/

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
[Arnout: write commit log]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>