EVM benchmark utilities (#8944)

* Make it possible to expose jsontests using feature flag

* Add start_stop_hook for jsontests

* Fix evmbin compile

* Implement vm jsontests times to tsv result

* Use /usr/bin/env to avoid errors on non-Debian systems

* Move evmbin/bench.sh to scripts and add vm_jsontests script for convenience

* Add tempdir as required deps for test-helpers

* Address grumbles on comments

* Detect file/folder automatically and add command docs

* Fix bench script

* times -> timings

* typo: wrong if condition

ethcore/src/json_tests/mod.rs

@@ -14,6 +14,8 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
+//! Helpers and tests for operating on jsontests.
+
 #[macro_use]
 mod test_common;
 
@@ -22,4 +24,21 @@ mod executive;
 mod state;
 mod chain;
 mod trie;
+
+#[cfg(test)]
 mod difficulty;
+
+pub use self::test_common::HookType;
+
+pub use self::transaction::run_test_path as run_transaction_test_path;
+pub use self::transaction::run_test_file as run_transaction_test_file;
+pub use self::executive::run_test_path as run_executive_test_path;
+pub use self::executive::run_test_file as run_executive_test_file;
+pub use self::state::run_test_path as run_state_test_path;
+pub use self::state::run_test_file as run_state_test_file;
+pub use self::chain::run_test_path as run_chain_test_path;
+pub use self::chain::run_test_file as run_chain_test_file;
+pub use self::trie::run_generic_test_path as run_generic_trie_test_path;
+pub use self::trie::run_generic_test_file as run_generic_trie_test_file;
+pub use self::trie::run_secure_test_path as run_secure_trie_test_path;
+pub use self::trie::run_secure_test_file as run_secure_trie_test_file;