It is complicated to add mocked-up symbols for pre-handling CRC.
Handle CRC after all the export symbols in the relevant module
are registered.

Call handle_modversion() after the handle_symbol() iteration.

In some cases, I see atand-alone __crc_* without __ksymtab_*.
For example, ARCH=arm allyesconfig produces __crc_ccitt_veneer and
__crc_itu_t_veneer. I guess they come from crc_ccitt, crc_itu_t,
respectively. Since __*_veneer are auto-generated symbols, just
ignore them.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>