Enable ASAN build

tools/asan_build

+#!/bin/bash
+
+# Build Skia with Address Sanitizer.
+#
+# Address Sanitizer is available in LLVM (and Clang) 3.1 and above, as well as
+# GCC 4.8.  For now, this script assumes the use of Clang 3.2 or newer, which
+# uses different flag syntax from 3.1.
+#
+# For more information, see:
+# https://code.google.com/p/address-sanitizer/wiki/AddressSanitizer
+
+makeVars="$@"
+
+export CC="$(which clang)"
+export CXX="$(which clang++)"
+export LINK="$(which clang)"
+
+noClang="Couldn't find Clang on this machine!"
+if [[ -z "${CC}" ]]; then
+  echo "${noClang}"
+  exit 1
+fi
+if [[ -z "${CXX}" ]]; then
+  echo "${noClang}"
+  exit 1
+fi
+if [[ -z "${LINK}" ]]; then
+  echo "${noClang}"
+  exit 1
+fi
+
+export GYP_DEFINES="skia_asan_build=1 ${GYP_DEFINES}"
+
+python gyp_skia
+if [[ "$?" != "0" ]]; then
+  exit 1
+fi
+
+make ${makeVars}
+if [[ "$?" != "0" ]]; then
+  exit 1
+fi