Copy existing arch libs from build dirs to current dist dir.

def distribute_libs(self, arch, src_dirs, wildcard='*', dest_dir="libs"):
        '''Copy existing arch libs from build dirs to current dist dir.'''
        info('Copying libs')
        tgt_dir = join(dest_dir, arch.arch)
        ensure_dir(tgt_dir)
        for src_dir in src_dirs:
            for lib in glob.glob(join(src_dir, wildcard)):
                shprint(sh.cp, '-a', lib, tgt_dir)