Allowing C99 standard

[Julien ÉLIE]

Hi all,

I suggest to change the current requirement that "all INN code should be 
written expecting ANSI C" (aka C89) to C99.  Modern compilers support 
C99 and I doubt we have still users of very old platforms without a 
C99-compliant compiler.

The rationale is that trying to build INN with -std=c89 already fails: 
innd/python.c and nnrpd/python.c cannot be built with Python 3.13 (for 
instance).  There are tons of errors coming from Python headers, like:

/usr/include/python3.13/cpython/pyatomic.h:96:8: error: unknown type 
name ‘inline’
/usr/include/python3.13/object.h:321:26: error: expected ‘=’, ‘,’, ‘;’, 
‘asm’ or ‘__attribute__’ before ‘Py_REFCNT’
etc.

Builds fine with -std=c99.


Apart from Python, a few other files do not build with C89.  They could 
easily be fixed though, some of them are even only in CURRENT (not 
released), but we can keep them as-is if we build with C99.  Examples:

commands.c:250:5: error: C++ style comments are not allowed in ISO C90
   250 |     // strlcpy(PERMpass, fields[3], sizeof(PERMpass));

hissqlite/hissqlite.c:823:9: error: 'for' loop initial declarations are 
only allowed in C99 or C11 mode
   823 |         for (size_t i = 0; writing && ok && i < n; i++) {
       |         ^~~



Also, it would permit the use of types like "unsigned long long" 
(without checking its availability and switching to "unsigned long" 
otherwise, which may not be sufficient), the %zu format specifier for 
size_t instead of casting it to "unsigned long" and using %lu, and maybe 
other things.

-- 
Julien ÉLIE

« La libertad, Sancho, es uno de los más preciosos dones que a los
   hombres dieron los cielos; con ella no pueden igualarse los tesoros
   que encierran la tierra y el mar: por la libertad, así como por la
   honra, se puede y debe aventurar la vida. » (Miguel de Cervantes
   Saavedra)