travis: Set CARGO_HOME to third_party/rust_crates (#1370)

Adds prebuilt hyperfine and sccache binaries 

Only build test_cc for LSAN

Add Cargo.lock

Only run benchmarks in master

tools/prebuilt.py

@@ -0,0 +1,37 @@
+import sys
+import os
+from util import run, root_path
+from third_party import tp, google_env
+
+
+def download_prebuilt(sha1_file):
+    run([
+        "python",
+        tp('depot_tools/download_from_google_storage.py'),
+        '--platform=' + sys.platform,
+        '--no_auth',
+        '--bucket=denoland',
+        '--sha1_file',
+        sha1_file,
+    ],
+        env=google_env())
+
+
+def load_sccache():
+    if sys.platform == 'win32':
+        p = "prebuilt/win/sccache.exe"
+    elif sys.platform.startswith('linux'):
+        p = "prebuilt/linux64/sccache"
+    elif sys.platform == 'darwin':
+        p = "prebuilt/mac/sccache"
+    download_prebuilt(p + ".sha1")
+    return os.path.join(root_path, p)
+
+
+def load_hyperfine():
+    if sys.platform == 'win32':
+        download_prebuilt("prebuilt/win/hyperfine.exe.sha1")
+    elif sys.platform.startswith('linux'):
+        download_prebuilt("prebuilt/linux64/hyperfine.sha1")
+    elif sys.platform == 'darwin':
+        download_prebuilt("prebuilt/mac/hyperfine.sha1")