Fix write() when the string being written is larger than the buffer.  This broke various ObjC testcases
with very long symbol names.

llvm-svn: 55148
diff --git a/llvm/lib/Support/raw_ostream.cpp b/llvm/lib/Support/raw_ostream.cpp
index b1209a2d..a5cf629 100644
--- a/llvm/lib/Support/raw_ostream.cpp
+++ b/llvm/lib/Support/raw_ostream.cpp
@@ -116,6 +116,7 @@
       assert(OutBufCur == OutBufStart);
       memcpy(OutBufStart, Ptr, NumToEmit);
       Ptr += NumToEmit;
+      Size -= NumToEmit;
       OutBufCur = OutBufStart + NumToEmit;
       flush_impl();
     }