Fix SWIGWORDSIZE64 incorrectly set on macOS, breaking arm64 builds

[Tuguberk]

Problem

Building fastdds_python on macOS arm64 (Apple Silicon) fails with type mismatch errors in the SWIG-generated wrapper:

fastddsPYTHON_wrap.cxx: error: cannot initialize return object of type
  'std::vector<unsigned long, std::allocator<unsigned long>> *'
  with an rvalue of type 'std::vector<unsigned long long> *'

Root cause

CMakeLists.txt sets SWIGWORDSIZE64 for all UNIX 64-bit platforms:

if(UNIX AND CMAKE_SIZEOF_VOID_P EQUAL 8)
    set_property(TARGET ${PROJECT_NAME} PROPERTY
        SWIG_COMPILE_DEFINITIONS SWIGWORDSIZE64)
endif()

When SWIGWORDSIZE64 is defined, SWIG's stdint.i maps uint64_t to unsigned long:

#if defined(SWIGWORDSIZE64)
typedef unsigned long int uint64_t;   // what SWIG assumes
#else
typedef unsigned long long int uint64_t;

On Linux x86_64 and aarch64, the system <cstdint> also defines uint64_t as unsigned long — so SWIGWORDSIZE64 is correct there.

On macOS (including arm64), the system <cstdint> defines uint64_t as unsigned long long. Because macOS is also a 64-bit UNIX system, the condition was true, causing a mismatch between SWIG's assumed type and the compiler's actual type for std::vector<uint64_t>.

Fix

Exclude Apple platforms from the SWIGWORDSIZE64 definition. On macOS, SWIG's fallback (unsigned long long) correctly matches the system type.

if(UNIX AND NOT APPLE AND CMAKE_SIZEOF_VOID_P EQUAL 8)

Testing

• Platform: macOS 15 Sequoia, Apple Silicon (arm64)
• Toolchain: SWIG 4.4.1, Apple Clang 17, Python 3.13
• FastDDS: v3.4.0 (fastdds_python v2.4.0)
• Full build succeeds: colcon build --packages-select fastdds_python
• Import verified: python3 -c "import fastdds; print(fastdds.DomainParticipantFactory)"