Add scripts for running LLVM coverage

tools/llvm_coverage.sh

Index: tools/llvm_coverage.sh
diff --git a/tools/llvm_coverage.sh b/tools/llvm_coverage.sh
new file mode 100755
index 0000000000000000000000000000000000000000..59d99e7a271cc16a275323846d8407bb1805caa2
--- /dev/null
+++ b/tools/llvm_coverage.sh
@@ -0,0 +1,16 @@
+#!/bin/sh
+# Copyright (c) 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Run from Skia repo like this:
+#   $ tools/llvm_coverage.sh dm
+# or
+#   $ tools/llvm_coverage.sh nanobench
+
+set -x
+set -e
+
+make clean
+tools/llvm_coverage_build $1

[mtklein, 2015/07/01 20:17:37]

Any reason not to fold tools/llvm_coverage_build right into here?  Not sure it
ever makes sense to have build-only coverage bots.

[borenet, 2015/07/06 12:06:35]

My plan is to run this bot as a new "coverage" flavor of the same recipe we use
for all bots.  That requires that we build and run separately.

+python tools/llvm_coverage_run.py $@