Fix more -Wcast-qual warnings.

llvm-svn: 101656
diff --git a/llvm/tools/llvm-ld/llvm-ld.cpp b/llvm/tools/llvm-ld/llvm-ld.cpp
index 29b74b8..ce52b59 100644
--- a/llvm/tools/llvm-ld/llvm-ld.cpp
+++ b/llvm/tools/llvm-ld/llvm-ld.cpp
@@ -399,7 +399,7 @@
 
   // Run the compiler to assembly and link together the program.
   int R = sys::Program::ExecuteAndWait(
-    gcc, &Args[0], (const char**)clean_env, 0, 0, 0, &ErrMsg);
+    gcc, &Args[0], const_cast<const char **>(clean_env), 0, 0, 0, &ErrMsg);
   delete [] clean_env;
   return R;
 }