[GOLD] Don't assert in powerpc stub_table

[Alan Modra]

A branch in a non-exec section that needs a stub can lead to this
assertion.

	* powerpc.cc (Powerpc_relobj::stub_table): Return NULL rather
	then asserting.

diff --git a/gold/powerpc.cc b/gold/powerpc.cc
index 7750e11..2699723 100644
--- a/gold/powerpc.cc
+++ b/gold/powerpc.cc
@@ -292,8 +292,8 @@ public:
 	  = static_cast<Target_powerpc<size, big_endian>*>(
 	      parameters->sized_target<size, big_endian>());
 	unsigned int indx = this->stub_table_index_[shndx];
-	gold_assert(indx < target->stub_tables().size());
-	return target->stub_tables()[indx];
+	if (indx < target->stub_tables().size())
+	  return target->stub_tables()[indx];
       }
     return NULL;
   }

-- 
Alan Modra
Australia Development Lab, IBM