FIX: use snprintf instead of sprintf

[ismagilli]

Modern compilers warn that the sprintf function is deprecated. I have added a call to snprintf function.

Note. Function snprintf appeared only in C99, so I added a check that the program compiles to the C99 standard and above. The gcc and clang compilers define the constant __STDC_VERSION__. The defined(__STDC_VERSION__) check is necessary because the __STDC_VERSION__ constant may not defined.

From man snprintf:

the snprintf() and vsnprintf() functions conform to ISO/IEC 9899:1999 (“ISO C99”)

[ismagilli]

Update commit text:

- FIX: use snprintf instead of sprintf
+ FIX: image_writer: use snprintf instead of sprintf