improved suppressions file for valgrind+python

I've learned how to glob function names and leave ellipses in call stacks, so
now this file suppresses all bogus warnings on my Ubuntu x86_64 laptop.
several extra self-checks in rsa.cpp

This is for https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1924#comment:7 .
test for overrun of the output buffer when reading

from /dev/urandom
always define CRYPTOPP_DISABLE_ASM=1

(see https://tahoe-lafs.org/trac/pycryptopp/ticket/85 )
disable asm only when we're building the embedded libcryptopp
remove ecdsa -- it has been replaced by ed25519
remove --disable-embedded-cryptopp, replace it
print out the version of pycryptopp in bench
fix two small errors noticed by sneves

https://tahoe-lafs.org/trac/pycryptopp/ticket/85#comment:15
I found yet another version number hidden in here.