package/jsoncpp: bump to version 1.6.5

Remove patch 0001-Revert-Use-std-namespace-for-snprintf.patch:
This patch was initially intented to remove upstream commit
1c58876185d2a4ed87dac4a54b82f607e74f55fd to disable std::snprintf() for all
compilers. However, the patch actually reverts upstream commit
240ddb6a1b7aae7c6528e328995812ee695a73af which only uses std namespace if the
compiler defines __cplusplus >= 201103L, thus is a recent C++11 compiler.

Furthermore, upstream commit fac87108a49fb1b2640eff5d8e4cc7a12723a510 adds
the `-std=c++11` compiler flag to gcc, so jsoncpp now requires a C++11 compiler
either way.

With jsoncpp requiring a recent C++11 compiler we need at least gcc 4.7.

Backport patch from upstream [1] to remove `-Werror` from the compiler flags to
allow building with CS ARM toolchains.

[1]
https://github.com/open-source-parsers/jsoncpp/commit/d7b84f69c5e92178e110552cce27f900744e1779



Cc: Baruch Siach <baruch@tkos.co.il>
Cc: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Reviewed-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>