PNaCl driver: Add libgcc to mixed native/bitcode links

pnacl/driver/pnacl-driver.py

Index: pnacl/driver/pnacl-driver.py
diff --git a/pnacl/driver/pnacl-driver.py b/pnacl/driver/pnacl-driver.py
index f6412d84950605698ef130a2e69d05252838205e..1b6bccadf1a36faba553b350ffe299992d9b4f73 100755
--- a/pnacl/driver/pnacl-driver.py
+++ b/pnacl/driver/pnacl-driver.py
@@ -497,8 +497,14 @@ def main(argv):
   # If -arch was given, we are compiling directly to native code
   compiling_to_native = GetArch() is not None
 
-  if env.getbool('ALLOW_NATIVE') and not compiling_to_native:
-    Log.Fatal("--pnacl-allow-native without -arch is not meaningful.")
+  if env.getbool('ALLOW_NATIVE'):
+    if not compiling_to_native:
+      Log.Fatal("--pnacl-allow-native without -arch is not meaningful.")
+    # For native/mixed links, also bring in the native libgcc to avoid link
+    # failure if pre-translated native code needs functions from it.
+    env.append('LD_FLAGS', env.eval('-L${LIBS_NATIVE_ARCH}'))
+    env.append('STDLIBS', '-lgcc')
+
 
   if not env.get('STDLIB'):
     # Default C++ Standard Library.