[java] Only emit methodObject when it's used

See #195

compiler/analyser.c

@@ -895,6 +895,9 @@ static struct node * make_among(struct analyser * a, struct node * p, struct nod
     }
     x->substring = substring;
     if (substring != 0) substring->among = x;
+
+    if (x->function_count > 0) ++a->among_with_function_count;
+
     return p;
 }
 
@@ -1612,6 +1615,7 @@ extern struct analyser * create_analyser(struct tokeniser * t) {
     a->program = 0;
     a->amongs = 0;
     a->among_count = 0;
+    a->among_with_function_count = 0;
     a->groupings = 0;
     a->mode = m_forward;
     a->modifyable = true;

compiler/generator_java.c

@@ -1194,9 +1194,11 @@ static void generate_class_begin(struct generator * g) {
     w(g, g->options->parent_class_name);
     w(g, " {~+~N"
          "~N"
-         "~Mprivate static final long serialVersionUID = 1L;~N"
-         "~Mprivate static final java.lang.invoke.MethodHandles.Lookup methodObject = java.lang.invoke.MethodHandles.lookup();~N"
-         "~N");
+         "~Mprivate static final long serialVersionUID = 1L;~N");
+    if (g->analyser->among_with_function_count > 0) {
+        w(g, "~Mprivate static final java.lang.invoke.MethodHandles.Lookup methodObject = java.lang.invoke.MethodHandles.lookup();~N");
+    }
+    w(g, "~N");
 }
 
 static void generate_class_end(struct generator * g) {

compiler/header.h

@@ -310,6 +310,7 @@ struct analyser {
     struct among * amongs_end;
     int among_count;
     int amongvar_needed;      /* used in reading routine definitions */
+    int among_with_function_count; /* number of amongs with functions */
     struct grouping * groupings;
     struct grouping * groupings_end;
     struct node * substring;  /* pending 'substring' in current routine definition */