Fixed a crash during stacktrace printing if addr2line failed to start.
Fixed a crash during stacktrace printing if addr2line failed to start.

In order to get all the input from addr2line we must read in a loop,
until the response is complete. Also, in case that the response is
malformed, we must not end up reading invalid memory.

natsys/mariadb_10.2,ollie314/server,ollie314/server,natsys/mariadb_10.2,flynn1973/mariadb-aix,ollie314/server,natsys/mariadb_10.2,ollie314/server,ollie314/server,ollie314/server,flynn1973/mariadb-aix,natsys/mariadb_10.2,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2,flynn1973/mariadb-aix,ollie314/server,natsys/mariadb_10.2,ollie314/server,ollie314/server,flynn1973/mariadb-aix,flynn1973/mariadb-aix,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,ollie314/server,flynn1973/mariadb-aix,flynn1973/mariadb-aix,flynn1973/mariadb-aix,flynn1973/mariadb-aix,ollie314/server