Add clear and deinit markmap (test)

cli_main.c

@@ -100,6 +100,7 @@ int main(int argc, char** argv) {
   for (int i = 0; i < ticks; ++i) {
     orca_run(&field, markmap_r.buffer);
   }
+  markmap_reusable_deinit(&markmap_r);
   field_fput(&field, stdout);
   field_deinit(&field);
   return 0;

sim.c

@@ -92,9 +92,9 @@ static inline void oper_m_phase1(Field* field, Usz y, Usz x) {
 }
 
 void orca_run(Field* field, Markmap_buffer markmap) {
-  (void)markmap;
   Usz ny = field->height;
   Usz nx = field->width;
+  markmap_clear(markmap, ny, nx);
   Glyph* field_buffer = field->buffer;
   // Phase 0
   for (Usz iy = 0; iy < ny; ++iy) {