Decrease number of threads in ExtensionRegistration tests for mips, current number is causing OOMs.

This was fixed for arm in revision 10045
Review URL: http://codereview.chromium.org/8662003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10047 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/cctest/test-lockers.cc

@@ -674,7 +674,7 @@ class IsolateGenesisThread : public JoinableThread {
 // Test installing extensions in separate isolates concurrently.
 // http://code.google.com/p/v8/issues/detail?id=1821
 TEST(ExtensionsRegistration) {
-#ifdef V8_TARGET_ARCH_ARM
+#if defined V8_TARGET_ARCH_ARM || defined V8_HOST_ARCH_MIPS
   const int kNThreads = 10;
 #else
   const int kNThreads = 40;