Fix -Wcast-qual warnings.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101786 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/InitHeaderSearch.cpp b/lib/Frontend/InitHeaderSearch.cpp
index b675df0..1a0ddf0 100644
--- a/lib/Frontend/InitHeaderSearch.cpp
+++ b/lib/Frontend/InitHeaderSearch.cpp
@@ -355,7 +355,7 @@
     else if (vs80comntools)
       vscomntools = vs80comntools;
     if (vscomntools && *vscomntools) {
-      char *p = (char*)strstr(vscomntools, "\\Common7\\Tools");
+      char *p = const_cast<char *>(strstr(vscomntools, "\\Common7\\Tools"));
       if (p)
         *p = '\0';
       path = vscomntools;