arch: posix: instruct native_sim to use 64-bit time_t

Use a 64-bit time_t on native_sim. This ensures that native_sim (and
hopefully also platforms based on it?) uses a 64-bit time_t type in
the native C library.

This is important to ensure that e.g. the Y2K bug isn't an issue,
among other things.

With that, the size of time_t in Zephyr is uniform across all
supported architectures and platforms.

Signed-off-by: Chris Friedt <cfriedt@tenstorrent.com>

Author: cfriedt

arch/posix/CMakeLists.txt

@@ -54,6 +54,8 @@ else() # Linux.x86_64
     zephyr_compile_options(-m32)
     zephyr_link_libraries(-m32)
 
+    zephyr_compile_options(-D__USE_TIME_BITS64=1)
+
     target_link_options(native_simulator INTERFACE "-m32")
     target_compile_options(native_simulator INTERFACE "-m32")