replace ENABLE_LIBCONFIG by HAVE_LIBCONFIG (use macro AC_CHECK_LIBdefault ACTION-IF-FOUND behavior)
fix unused write result in undefined HAVE_EXECINFO_H case
remove -lssl from Makefile.in
please add AC_CHECK_LIB([ssl], [function-name]) to configure.ac in the case of failed linkage
Merge pull request #60 from antma/master

minor configure.ac simplifications