GUAC-597: Add new autoconf files to .gitignore.
GUAC-597: Remove unnecessary dlopen() test, add automatically generated dlopen() test result to Makefile.am.
GUAC-598: Fix warning regarding unsigned comparison against zero.
GUAC-598: Bring up to compliance with POSIX standard claimed by source.
GUAC-598: Remove unneeded _BSD_SOURCE define.
GUAC-598: Use unsigned instead of u_ type.
GUAC-598: Fix warnings against SSH.