improve compat with certain versions of GCC (on cygwin?)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30054 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachOWriter.cpp b/lib/CodeGen/MachOWriter.cpp
index 17001fc..0f6820e 100644
--- a/lib/CodeGen/MachOWriter.cpp
+++ b/lib/CodeGen/MachOWriter.cpp
@@ -197,7 +197,7 @@
   // desired section alignment, which must be at least as much as required by
   // this symbol.
   if (Align) {
-    Sec.align = std::max(Sec.align, Align);
+    Sec.align = std::max(unsigned(Sec.align), Align);
     Sec.size = (Sec.size + Align - 1) & ~(Align-1);
   }
   // Record the offset of the symbol, and then allocate space for it.