jansson 2.11

Document encoding requirements for callbacks

Fix generated `pkg-config` file using cmake.

Use a more specific error code for premature end of input

document that json_error_code will be added in version 2.11

Original patch by @phst.

Fixes #369.

Add json_sprintf and json_vsprintf

Fixes #392

Atomic references and thread safe json_dump

Clarify thread safety docs, rename JANSSON_THREAD_SAFE

Fixes #387

Circular reference detection in json_dump was not thread safe.  Replace
visited flag with a hashtable_t.

Issue #387

This makes use of __atomic or __sync builtin compiler functions to make
json_decref and json_incref thread-safe.

Issue #387

json_pack: Enable more complete stealing of references.

The `O` format causes reference counts to increase, but in an error they
are not released.  Callers to unpack functions that use the `O` format
should use pointers pre-initialized to NULL so they can safely release
the reference on error.

Also corrected typo which said this was like `O` (itself).

Fixes #135

This function needs to release a reference to value if the other
arguments are invalid.

Issue #135

Users of the "o" format have an expectation that the object reference
will be stolen.  Any error causes the collection process to end early.
This patch causes json_pack and related functions to continue scanning
the format and parameters so all references can be stolen to prevent
leaks.  This makes no attempt to continue processing if the format
string is broken or missing.

'make check' still passes.  Ran test_pack under valgrind and verified
that the leaked reference is fixed. Added a test which uses refcounts
to verify that the reference was correctly stolen after a NULL value
error.

Issue #135

Fixes akheron/jansson#373

Remove extra reference actions in parsers.

Document that length-aware string functions have been added in 2.7

Make parse_object use json_object_set_new_nocheck and make parse_array
use json_array_append_new, remove json_decref from error and success
paths.

Fixes #376

'sys/time.h' is a typo, it should read: 'sys/types.h'

Reported by Diederick Huijbers

Fixed the generated `jansson.pc` with cmake to be consistent with the
one generated using GNU Autotools.

Use last byte of error text as numeric error code

Fixes #352

Fixes #344

json_dump_file API returns success even when fclose fails

json_dump_file API returns success even when fclose fails (consider disk full case). API should check the return value of fclose before returning success to its caller. fwrite may not write anything into the file, it simply returns the number of bytes written into the buffer. When disk is full and fclose is called, it results in truncation of the file (resulting in zero sized file). Since, API is returning success, its caller can't take any remedial action on its failure.

Docs - Fix typo

Enable optional object members in json_pack()