use assert(0) instead of exit(1)

When a fatal error (unaligned memory etc.) is detected, jerasure
should assert(3) instead of exit(3) to give a chance to the calling
program to catch the exception and display a stack trace. Although it is
possible for gdb to display the stack trace and break on exit, libraries
are not usually expected to terminate the calling program in this way.

Signed-off-by: Loic Dachary <loic@dachary.org>
decoder: allow for path len > 100 characters

It's not that uncommon to have path longer than 100 characters.

Signed-off-by: Loic Dachary <loic@dachary.org>
decoder/encoder: fix compilation warnings

Resolve compilation warnings about unused variables and function return
values being ignored.

Signed-off-by: Loic Dachary <loic@dachary.org>
tests: fail if gf_methods is not found

If the gf_methods was not found, the test would silently succeed doing
nothing. Check for existence and fail if it is not in the path.

Signed-off-by: Loic Dachary <loic@dachary.org>
tests: add minimal encoder/decoder test

Add a test to run with make check to run encoder and decoder to make
sure they work at least in one simple case. It is also useful as a
documentation about how to use them.

Signed-off-by: Loic Dachary <loic@dachary.org>
Merge pull request #2 from dachary/wip-exit

Merging a set of commits from Loic: Use assert(0) to exit(1) and clean-up some of the test code.