c6x/* "facelift":

- make scripts executable;
- "parameterize" platform selection in c6x/do_fips;
- add c6x/fips_algvs.mak;
- add c6x/run6x.js launcher for more recent CCS versions;

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Stephen Henson <steve@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4265)