Check output of write() to stdout, updated -quiet documentation

Check for errors on write and log errors. This is likely to cause a
SIGPIPE on failure anyway, and there is no reason to explicitly abort
since this is basically debug output.

Update builtin -quiet doc to match the manpage documentation, which
explains why this isn't using BIO like the rest of the surrounding code:

https://www.openssl.org/docs/apps/s_server.html
do not include public headers as though they are local

Avoid having to use -I trickery to find public header files included as
though they are private.
remove parsing of -rand options in openssl apps

Since the random number generator no longer allows being seeded, remove
support for parsing the unused -rand option and the unused random buffer
variables. Better to fail than to be surprised when the RNG seed does not
function as expected.

This fixes compiler warnings about unused random seed variables.
avoid defining struct pqueue typedef twice

with pqueue moving to a private interface, the typedef can occur twice

../include/openssl/dtls1.h:147:25: error: redefinition of typedef 'pqueue' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct _pqueue *pqueue;
                        ^
../include/pqueue.h:63:25: note: previous definition is here
typedef struct _pqueue *pqueue;