filebuf.c: fix unused-but-set warning

Fix a bug and GCC warning introduced in 932669b8

Fix up examples code

Add checks for NULL to the config and remote free functions

Fix git_status_foreach tests

Don't use '__attribute__ visibility' with gcc unless it's at version 4 or better

version 4 or better.

There were quite a few places were spaces were being used instead of
tabs. Try to catch them all. This should hopefully not break anything.
Except for `git blame`. Oh well.

1. The license header is technically not valid if it doesn't have a
copyright signature.

2. The COPYING file has been updated with the different licenses used in
the project.

3. The full GPLv2 header in each file annoys me.

Provided the tests fail (which they should not) and the callback is invoked too many times, this prevents the tests from segfaulting.

This allows to build both test suites at the same time

...Ops, I broke the old test when porting it to Clay.

Reverted signature of git_signature_new.
Removed error check wrappers (voted down). Made Makefile
work out of the box on Linux and Solaris when standard
cmake build instructions for the library are followed.

 - Should increase performance through usage of a walker
 - No callback invocation for unaltered entries

 - fix retrieval of a file status when working against a newly initialized repository
 - reduce memory pressure
 - prevents a directory from being tested

Document GIT_SUCCESS

change to the signature of an API function (git_signature_new).
Also, the examples/general.c had a lot of unchecked return values
which were addresed with a couple of macros. The resulting example
still does not work correctly but at least now it fails with an
error message rather than not compiling or dumping core. Example
runtime issues may be addressed in a later commit.

Signed-off-by: Carlos Martín Nieto <carlos@cmartin.tk>

For unsigned types, the comparison >= 0 is always true, so avoid it by using
a post-decrement and integrating the initial assigment into the loop body.
No change in behavior is intended.

write_deflate() used to ignore errors by zlib's deflate function when
not compiling in DEBUG mode. Always read $result and throw an error
instead.

Signed-off-by: schu <schu-github@schulog.org>

Warning fixes

pull request for #387