Add error for EBADARCH

That's apparently errno 86 on macOS, and it's triggered when the
architecture is wrong.

I'll leave other macOS errors to the macOS users.

See #9052.

(cherry picked from commit 60f87ef3be)

CHANGELOG.rst

@@ -7,6 +7,7 @@ This release of fish introduces the following small enhancements:
 - ``printf`` returns a better error when used with arguments interpreted as octal numbers (:issue:`9035`).
 - New completions for ``qdbus`` (:issue:`9031:`) and ``reflector`` (:issue:`9027`), and improvements to some completions.
 - ``history merge`` when in private mode is now an error, rather than wiping out other sessions' history (:issue:`9050`).
+- The error message when launching a command that is built for the wrong architecture on macOS is more helpful (:issue:`9052`).
 
 This release also fixes a number of problems identified in fish 3.5.0.
 

src/postfork.cpp

@@ -543,6 +543,14 @@ void safe_report_exec_error(int err, const char *actual_cmd, const char *const *
                        actual_cmd);
             break;
         }
+#ifdef EBADARCH
+        case EBADARCH: {
+            FLOGF_SAFE(exec,
+                       "Failed to execute process '%s': Bad CPU type in executable.",
+                       actual_cmd);
+            break;
+        }
+#endif
         default: {
             char errnum_buff[64];
             format_long_safe(errnum_buff, err);