This is a cherry-pick of 89c844d back to 0.12.

jmcorgan · jmcorgan · commit 9462e791b7de · 2016-06-08T06:41:03.000-07:00
===== Re-instate TARGET_OS=linux in configure.ac. Removed by 351abf9.
diff --git a/configure.ac b/configure.ac
@@ -336,6 +336,7 @@ case $host in
      OBJCXXFLAGS="$CXXFLAGS"
      ;;
    *linux*)
+     TARGET_OS=linux
      LEVELDB_TARGET_FLAGS="-DOS_LINUX"
      ;;
    *)
