PR 17916: Don't fail if xcrun is not present.

llvm-svn: 194745

clang/test/lit.cfg

@@ -359,11 +359,14 @@ if use_gmalloc:
 # On Darwin, support relocatable SDKs by providing Clang with a
 # default system root path.
 if 'darwin' in config.target_triple:
-    cmd = subprocess.Popen(['xcrun', '--show-sdk-path'],
-                           stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-    out, err = cmd.communicate()
-    out = out.strip()
-    res = cmd.wait()
+    try:
+        cmd = subprocess.Popen(['xcrun', '--show-sdk-path'],
+                               stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        out, err = cmd.communicate()
+        out = out.strip()
+        res = cmd.wait()
+    except OSError:
+        res = -1
     if res == 0 and out:
         sdk_path = out
         lit_config.note('using SDKROOT: %r' % sdk_path)