Remove a bunch of unused variables.

Removed or commented out to stop compiler whining about them.
Signed-off-by: Patrick Hogan <pbhogan@gmail.com>

src/hash.c

@@ -164,7 +164,6 @@ mrb_hash_set(mrb_state *mrb, mrb_value hash, mrb_value key, mrb_value val) /* mr
 {
   khash_t(ht) *h;
   khiter_t k;
-  int r;
 
   mrb_hash_modify(mrb, hash);
   h = RHASH_H_TBL(hash);

src/kernel.c

@@ -628,9 +628,7 @@ mrb_obj_init_copy(mrb_state *mrb, mrb_value self)
 mrb_value
 mrb_obj_instance_eval(mrb_state *mrb, mrb_value self)
 {
-  mrb_value *argv;
-  int argc;
-  mrb_value b, klass;
+  mrb_value b;
 
   mrb_get_args(mrb, "&", &b);
   return mrb_yield_with_self(mrb, b, 0, 0, self);

src/variable.c

@@ -61,7 +61,6 @@ mrb_gc_mark_iv(mrb_state *mrb, struct RObject *obj)
 size_t
 mrb_gc_mark_iv_size(mrb_state *mrb, struct RObject *obj)
 {
-  khiter_t k;
   struct kh_iv *h = obj->iv;
 
   if (!h) return 0;

src/vm.c

@@ -877,9 +877,11 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
       int o  = (ax>>13)&0x1f;
       int r  = (ax>>12)&0x1;
       int m2 = (ax>>7)&0x1f;
+      /* unused
       int k  = (ax>>2)&0x1f;
       int kd = (ax>>1)&0x1;
       int b  = (ax>>0)& 0x1;
+      */
       int argc = mrb->ci->argc;
       mrb_value *argv = regs+1;
       int len = m1 + o + r + m2;
@@ -953,7 +955,6 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
 
       if (mrb->exc) {
 	mrb_callinfo *ci;
-	int ridx;
 
       L_RAISE:
 	ci = mrb->ci;