Improve error handling in autogen.sh

While working on adding fuzzer support I ran into errors which didn't cause the "autoreconf" program to fail, leaving me to work with outdated files until I noticed. Turning all warnings into failures helps. There should be no errors in pristine source trees.

The message was as follows (resolved by prefixing the library name with "lib"):

fuzzing/Makefile.am:7: error: 'standalone.a' is not a standard library name fuzzing/Makefile.am:7: did you mean 'libstandalone.a'? fuzzing/Makefile.am: installing './depcomp'

Also set "-e" to exit the shell when an error occurs.