Move the compiler back to 4.8.1 + more small fixes

Summary:
1. Moved the compiler back to 4.8.1 and uses Centos 5.2 binaries if OS is Centos 5.2.

2. Fixes this issue: https://github.com/facebook/rocksdb/issues/7

3. We use lot of c++11 features, so we can't pretend we can compile without them. Makes it a first class dependency.

4. Fix blob_store_test, which failes on Ubuntu with "too many files opened" error

5. Removed dependency on port/port_chromium.h, which does not even exist on our system

Test Plan: make clean; make check

Reviewers: dhruba, kailiu

Reviewed By: kailiu

CC: leveldb

Differential Revision: https://reviews.facebook.net/D14145

util/blob_store_test.cc

@@ -144,7 +144,7 @@ TEST(BlobStoreTest, CreateAndStoreTest) {
                        Env::Default());
   vector<pair<Blob, string>> ranges;
 
-  for (int i = 0; i < 20000; ++i) {
+  for (int i = 0; i < 2000; ++i) {
     int decision = rand() % 5;
     if (decision <= 2 || ranges.size() == 0) {
       string buf;