rng-tools bug fix update
Bug fix update containing the following fixes:
- Fixed texrels on on rdrand_asm.S for pic compilation
- allow use of libargp if libc lacks argp parsing
- explicitly link against -lcrypto, fixing build in pkcs11 entropy source
- replace pthread_yield with posix compliant sched_yield
- bias rngd to use faster sources of entropy when available, falling back to slower sources when needed
- Fix a shutdown delay resulting from a thread exit race
- Fix a few minor compilation warnings
- Fix make distcheck make target
- Minor typo fixes/cleanups