binding_c needs "proper" prototypes

[eboasson]

Required information

Operating system:
E.g. maxOS 12.2.1

Compiler version:
E.g. Apple clang version 13.0.0 (clang-1300.0.29.30)

Observed result or behaviour:
Compiler warnings when compiling Cyclone DDS with Iceoryx 2.0 branch:

/Users/erik/C/iceoryx/install/include/iceoryx/v1.91.0/iceoryx_binding_c/config.h:23:32: warning: this function declaration is not a prototype [-Wstrict-prototypes]
uint32_t iox_cfg_max_publishers();
                               ^
                                void

Expected result or behaviour:
No warnings

Conditions where it occurred / Performed steps:
Build Cyclone DDS including eclipse-cyclonedds/cyclonedds#1175 with default compilation setting on aforementioned platform.