llvm_coverage_build: Use CC and CXX variables by default
NOTRY=true
BUG=skia:2430
Review URL: https://codereview.chromium.org/1242573003
diff --git a/tools/llvm_coverage_build b/tools/llvm_coverage_build
index 07b547f..85e9db9 100755
--- a/tools/llvm_coverage_build
+++ b/tools/llvm_coverage_build
@@ -7,12 +7,13 @@
#
# $ tools/llvm_coverage_build [any other flags to pass to make...]
#
-# This script assumes the use of Clang >=3.6.
+# This script assumes the use of Clang 3.6. Earlier versions do not support
+# the flags we use in the build, and 3.7+ hit asserts during compilation.
#
set -e
-export CC="$(which clang)"
-export CXX="$(which clang++)"
+export CC="${CC:-$(which clang)}"
+export CXX="${CXX:-$(which clang++)}"
if [[ -z "${CC}" ]] || [[ -z "${CXX}" ]]; then
echo "Couldn't find Clang on this machine!"