Also, emit the input string in the output so it's easier to see what's going on.

OSX) always include the _json_c_strerror function but only enable it with a flag
 during tests.

If we want to override `strerror()` in libjson-c
to make tests consistent across platforms, we
need to do it build-wide as configure/build
option.

Apple linkers make it really hard to override functions
at link-time, and this seems to be locked down on travis-ci.org
[ for security reasons I assume ].
While I got it to work locally, it did not work
when running on travis.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

Which now seems to fail the build.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

More code compression/de-duplication.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

Add a test that triggers the problem to ensure it stays fixed.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

Also, there's no need to worry about output consistency here, since it'll be
 different anyway due to different pointer values.

Improve json_object -> string performance

Hawciz pointed out that the previous commit modifies the public
interface of printbuf. Per his suggestion, sprintbuf() was restored
and a new pair of macros was added that wraps printbuf_memappend().

Using a wrapper macro instead of modifying sprintbuf() also reduces
function call overhead, bringing total performance gains to
approximately 400%.

Removes variadic prints for ~3x performance improvement.

closes https://github.com/json-c/json-c/issues/278

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

I got this on Mac OS X at least.
Not sure if it shows up in other envs

error:
```
strerror_override.c:53:13: error: incompatible redeclaration of library function 'strerror' [-Werror,-Wincompatible-library-redeclaration]
const char *strerror(int errno_in)
```

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

Json object set xxx

Conflicts:
	tests/test_util_file.c

Conflicts:
	tests/test_util_file.c

The test is implied in test1.

The idea is to check that the returned lengths and strings
are identical to what is expected to return the already
tested function 'json_object_to_json_string_ext'.

Signed-off-by: José Bollo <jose.bollo@iot.bzh>

Also, be sure the right locale_t is freed if we fail on the second uselocale.
Finally, fix test_locale so it *doesn't* use json_object_to_json_string as
 that will simple re-emit the original parsed string values.

The function fstat isn't declared without this include
on debian strect/sid and Fedora-23

Change-Id: I660a32ff173dcba04674aed51ed855b4fa55ac67
Signed-off-by: José Bollo <jose.bollo@iot.bzh>