Make handle stack size configurable like memory (#257)

This PR resolves #156

runtime.c

···
   as_variant(variant)->value = value;
 }
 
-#define MAX_HANDLES 4096
-
 struct handle_scope {
   struct object*** base;
 };
 
-static struct object** handle_stack[MAX_HANDLES];
+#ifndef HANDLE_STACK_SIZE
+#define HANDLE_STACK_SIZE 4096
+#endif
+
+static struct object** handle_stack[HANDLE_STACK_SIZE];
 static struct object*** handles = handle_stack;
 #ifndef NDEBUG
 // Only used to check for handle stack overflow.
-static struct object*** handles_end = &handle_stack[MAX_HANDLES];
+static struct object*** handles_end = &handle_stack[HANDLE_STACK_SIZE];
 #endif
 
 void pop_handles(void* local_handles) {

scrapscript.py

···
         cflags = discover_cflags(cc, args.debug)
         if args.memory:
             cflags += [f"-DMEMORY_SIZE={args.memory}"]
+        if args.handle_stack_size:
+            cflags += [f"-DHANDLE_STACK_SIZE={args.handle_stack_size}"]
         ldflags = env_get_split("LDFLAGS")
         subprocess.run([*cc, "-o", "a.out", *cflags, args.output, *ldflags], check=True)
 
···
     comp.add_argument("--format", action="store_true")
     comp.add_argument("--compile", action="store_true")
     comp.add_argument("--memory", type=int)
+    comp.add_argument("--handle-stack-size", type=int)
     comp.add_argument("--run", action="store_true")
     comp.add_argument("--debug", action="store_true", default=False)
     comp.add_argument("--check", action="store_true", default=False)