Fix logic of exit_reason memory handling.

This is temporary fix as opposed to what is implemented in feature/smp.

`exit_reason` should be allocated in the target process. If it is allocated
in the ctx process, it will be copied to the target process during its next
garbage collection, however this will impact the used memory size, which is
used to ensure a given number of free terms. If `MIN_FREE_SPACE_SIZE` is lower
than the size of the exit reason, the GC will allocate less bytes than expected.

Signed-off-by: Paul Guyot <[email protected]>

Author: pguyot

src/libAtomVM/context.c

@@ -187,7 +187,13 @@ static void context_monitors_handle_terminate(Context *ctx)
 
                 mailbox_send(target, info_tuple);
             } else {
-                target->exit_reason = memory_copy_term_tree(&ctx->heap_ptr, ctx->exit_reason, &ctx->mso_list);
+                size_t estimated_mem_usage = memory_estimate_usage(ctx->exit_reason);
+                if (UNLIKELY(memory_ensure_free(target, estimated_mem_usage) != MEMORY_GC_OK)) {
+                    //TODO: handle out of memory here
+                    fprintf(stderr, "Cannot handle out of memory.\n");
+                    AVM_ABORT();
+                }
+                target->exit_reason = memory_copy_term_tree(&target->heap_ptr, ctx->exit_reason, &target->mso_list);
 
                 // TODO: this cannot work on multicore systems
                 // target context should be marked as killed and terminated during next scheduling