Use reserveExtra in proxygen/lib/http/codec/compress/experimental/sim…

…ulator/CompressionUtils.cpp

Summary:
This code contains an instance of:
```
container.reserve(container.size()+N)
```
If called repeatedly on the same container, performance will be bad. It's safer to use:
```
reserveExtra(container, N)
```

See [this post](https://fb.workplace.com/groups/638005567605797/posts/1066088434797506) for more details.

Reviewed By: r-barnes

Differential Revision: D48692107

fbshipit-source-id: 21e90d079bcbeeb54209a0276e0f45820de3319c

proxygen/lib/http/codec/compress/experimental/simulator/CompressionUtils.cpp

@@ -6,6 +6,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+#include "common/base/ReserveUtils.h"
 #include <proxygen/lib/http/codec/compress/experimental/simulator/CompressionUtils.h>
 
 #include <proxygen/lib/http/HeaderConstants.h>
@@ -111,7 +112,7 @@ std::vector<compress::Header> prepareMessageForCompression(
         if (code == HTTP_HEADER_COOKIE) {
           vector<folly::StringPiece> cookiePieces;
           folly::split(';', value, cookiePieces);
-          cookies.reserve(cookies.size() + cookiePieces.size());
+          facebook::memory::reserveExtra(cookies, cookiePieces.size());
           for (auto cookie : cookiePieces) {
             cookies.push_back(ltrimWhitespace(cookie).str());
             allHeaders.emplace_back(code, name, cookies.back());