Remove `time_t` from API (bug #61821). The bit-width of `time_t` might change depending on compile time switches. That can cause a mismatch between class declarations in public headers and the actual alignment of the compiled classes. Avoid that problem by not using `time_t` in (public) headers. * build-aux/mk-octave-config-h.sh, oct-conf-post.in.h: Define OCTAVE_TIME_T to `int64_t`. The type of `time_t` is not defined in the C/C++ standards. However in all(?) implementations, it's either a signed 32-bit or a signed 64-bit integer. Use a signed 64-bit integer for storing those values in Octave classes. * other files: Use OCTAVE_TIME_T instead of `time_t`. Don't include <ctime> in files where it's not needed.

--- a/libinterp/corefcn/fcn-info.cc	Thu Mar 10 18:58:29 2022 +0100
+++ b/libinterp/corefcn/fcn-info.cc	Sat Feb 26 13:46:48 2022 +0100
@@ -603,7 +603,7 @@
                         // Same file.  If it is out of date, then reload it.
 
                         sys::time ottp = fcn->time_parsed ();
-                        time_t tp = ottp.unix_time ();
+                        OCTAVE_TIME_T tp = ottp.unix_time ();
 
                         fcn->mark_fcn_file_up_to_date (sys::time ());