Extending the maximum length of a boot classpath.

Running dalvikvm on a simulator causes path lengths to grow longer
because '/system' is prefixed with the full path to the android build
tree.
diff --git a/vm/analysis/DexPrepare.c b/vm/analysis/DexPrepare.c
index 3e65594..2bf33a3 100644
--- a/vm/analysis/DexPrepare.c
+++ b/vm/analysis/DexPrepare.c
@@ -1030,7 +1030,7 @@
  * If this changes, update DEX_OPT_MAGIC_VERS.
  */
 static const size_t kMinDepSize = 4 * 4;
-static const size_t kMaxDepSize = 4 * 4 + 1024;     // sanity check
+static const size_t kMaxDepSize = 4 * 4 + 2048;     // sanity check
 
 /*
  * Read the "opt" header, verify it, then read the dependencies section