sprintf -> snprintf conversion, from Vladimir Kirillov

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@118478 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/DocumentXML.cpp b/lib/Frontend/DocumentXML.cpp
index 894f230..e4526ba 100644
--- a/lib/Frontend/DocumentXML.cpp
+++ b/lib/Frontend/DocumentXML.cpp
@@ -104,7 +104,7 @@
       if (isprint(C))
         value += C;
       else {
-        sprintf(buffer, "\\%03o", C);
+        snprintf(buffer, sizeof(buffer), "\\%03o", C);
         value += buffer;
       }
       break;