Strip binaries on Linux (facebook#195)

Summary:
Our Linux binaries are currently not stripped, adding an unnecssary
~30MB to the NPM.
Pull Request resolved: facebook#195

Reviewed By: mhorowitz

Differential Revision: D20318363

Pulled By: willholen

fbshipit-source-id: f3f15917240f0cd9de8c3abc92dbbfc1e2e6f1b9

.circleci/config.yml

@@ -117,7 +117,7 @@ jobs:
           name: Build Hermes for Linux
           command: |
             cd "$HERMES_WS_DIR"
-            hermes/utils/build/configure.py --static-link --distribute
+            hermes/utils/build/configure.py --static-link --distribute --cmake-flags="-DCMAKE_CXX_FLAGS=-s"
             cd build_release
             ninja github-cli-release
       - run: