When a PUSH request fails to connect back, ban target IP:port for 5 minutes.

The aim is to limit the needless connection attempts to a non-responsive host.
The ban applies only to subsequent PUSH requests towards the same IP:port.
Prefer entropy_minirand() to entropy_rand31() since the former behaves better.

The flaw can be witnessed by running:

	random-test -B -p 100000 -F 0xffffffff -1
	random-test -B -p 100000 -F 0xffffffff -2

The output of the former command exhibits an anomaly in bit #10, which does
not appear with the second command.  The flaw stems from the weakness of the
underlying rand31() algorithm, of course, but the composition done in the
entropy_minirand(), which is the same as the one done for rand31_u32(), seems
to yield better distribution. The proof of that origin comes from running:

	random-test -B -p 100000 -F 0xffffffff
	random-test -B -p 100000 -F 0xffffffff -u

which compares rand31() and rand31_u32() and leads to a similar flaw / fix.
Allow random-test to brute-force search periods that span more than 32 bits.
For consistency, renamed thread-local PRNG routines as xxx_thread_rand*().

This concerned the ARC4 and Mersenne Twister PRNGs which used inconsistent
naming compared to the more recent implementations (AJE, CMWC, WELL).
Double the maximum size of array we can shuffle during entropy collection.

Because the number of bits used for the context of entropy_rand31() is 191,
we have largely enough entropy to reach all the permutations of arrays of
size 24, since 24! is about 2**79.04.

Being able to permute a larger size means we can shuffle more entropy gathering
routines at the same time, increasing the set of possible initial values.
entropy_seed(): use rand31_u32() to permute collection of the initial seed.
Added peek_be32_advance() and peek_le32_advance().
Ditched entropy_rand31(), and made entropy_minirand() use the KISS PRNG.

Since the introduction of entropy_seed(), we were gathering extra bits of
random context, so it was counter-productive to keep using rand31() when we
are in a position to use a better PRNG, which only requires 128 bits of initial
context to run.

As a bonus, this lets us increase the maximum size for a shuffled array to 33,
since the period of the KISS algorithm is at least 2**125.
entropy_collect_minirand(): collect more random numbers.
entropy_seed(): extract more entropy from the current usec counter.
entropy_collect_vmm(): collect more pointers from VMM.
aje_init(): feed more entropy to ensure we can spread it over all the pools.

Since entropy is randomly dispatched to pools, and we want to at initialize
most of them, we need to feed enough initial entropy so that, statistically,
we can reach all the pools.
rand31_random_seed(): increased amount of entropy used to gather initial seed.
entropy_seed(): collect even more initial entropy.
entropy_collect_cpu(): randomly shuffle the registers saved in the context.
Added entropy_collect_garbage() to collect from random items left on the stack.
entropy_seed(): include a re-seeding of the rand31() PRNG.