configure: v8_use_snapshot should be true

`v8_use_snapshot` should be either `true` or `false`, not 1 or 0.

PR-URL: https://github.com/nodejs/node/pull/3962
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>

configure

@@ -777,7 +777,7 @@ def configure_v8(o):
   o['variables']['v8_no_strict_aliasing'] = 1  # Work around compiler bugs.
   o['variables']['v8_optimized_debug'] = 0  # Compile with -O0 in debug builds.
   o['variables']['v8_random_seed'] = 0  # Use a random seed for hash tables.
-  o['variables']['v8_use_snapshot'] = 0 if options.without_snapshot else 1
+  o['variables']['v8_use_snapshot'] = 'false' if options.without_snapshot else 'true'
 
 def configure_openssl(o):
   o['variables']['node_use_openssl'] = b(not options.without_ssl)