Update documentatin for Eina Lock

Backport from commit 74556a3f901587f807758a4411a59738696796a9
on https://git.enlightenment.org/core/efl.git
eina_value_free() now takes NULL.

Backport from commit a3927ca1a7605899b9c55309ee9f5484ae77aae4
on https://git.enlightenment.org/core/efl.git
do not use EINA_FALSE instead of NULL

Backport from commit f8c2c574062339bfda4988a450e3f809451941e1
on https://git.enlightenment.org/core/efl.git
Fix unused var warning when not building on linux.

Backport from commit 3ab1b8afd843fd72676ccfd86376b239d766efe8
on https://git.enlightenment.org/core/efl.git
Fix warnings on calls to iconv, on freebsd.

Backport from commit 19e0422adf6843200cfffaaad88aa86ad813d69e
on https://git.enlightenment.org/core/efl.git
simplifie logic to not go with multiple level of callback for just getting the first entry in a hash.

Backport from commit f7fd1f1c84a9355039b38725c820b675f6dafc20
on https://git.enlightenment.org/core/efl.git
remove logically dead code.

The for loop above would exit with at least length = 0, so < 0 is
just impossible.

Backport from commit b67860e98fbead33f5553ff6ee091997ea924f96
on https://git.enlightenment.org/core/efl.git
let's check for returned value of realloc.

Backport from commit 8f817ff4a009b685a3d47d6a6115df01d4dc6efa
on https://git.enlightenment.org/core/efl.git
remove logically dead code.

Removing this code let me wonder what could be an int value that is not 0,
not < 0 and not > 0...

Backport from commit c33acef5d717527f9940d034dcbb0a8e6d060059
on https://git.enlightenment.org/core/efl.git
remove logically dead code.

I am wondering why this code was around, an useless variable and an if
that would never be taken...

Backport from commit 74121c14cd5c1fe787baf569f7db4730a637e31f
on https://git.enlightenment.org/core/efl.git
removing more dead code looking for strange int.

CID 1039941.

Backport from commit 344690554ad7d4397e9cee4618b1d9591c30d468
on https://git.enlightenment.org/core/efl.git
fix typo in matrixsparce.

CID 98417.

Backport from commit 2dd6e7f302c600936d0a5f870298b7b1f16656ae
on https://git.enlightenment.org/core/efl.git
leave a comment for CID 1039688.

Backport from commit caa2ec1b296a8a51b98e174289293a1b0224daf3
on https://git.enlightenment.org/core/efl.git
fix possible access to NULL.

CID 1039422.

Backport from commit adbb9ca1e32b424fcaf2753f3139350cc683123d
on https://git.enlightenment.org/core/efl.git