Minor fixes.

Quieted a couple of warnings about constness.

Added "synchronized" to BootClassLoader.getInstance(), which creates the
instance on first use.

Change-Id: I4a521bb2c6853b1ad8a118aa53f697be18b69280
diff --git a/vm/alloc/MarkSweep.c b/vm/alloc/MarkSweep.c
index 459a238..223448a 100644
--- a/vm/alloc/MarkSweep.c
+++ b/vm/alloc/MarkSweep.c
@@ -357,7 +357,7 @@
  */
 static void scanStaticFields(const ClassObject *clazz, GcMarkContext *ctx)
 {
-    StaticField *f;
+    const StaticField *f;
     int i;
 
     //TODO: Optimize this with a bit vector or something
diff --git a/vm/oo/Object.c b/vm/oo/Object.c
index fdb1a69..0d2da1f 100644
--- a/vm/oo/Object.c
+++ b/vm/oo/Object.c
@@ -85,7 +85,7 @@
 StaticField* dvmFindStaticField(const ClassObject* clazz,
     const char* fieldName, const char* signature)
 {
-    StaticField* pField;
+    const StaticField* pField;
     int i;
 
     assert(clazz != NULL);
@@ -100,7 +100,7 @@
         if (strcmp(fieldName, pField->field.name) == 0 &&
             strcmp(signature, pField->field.signature) == 0)
         {
-            return pField;
+            return (StaticField*) pField;
         }
     }