sanitise sign comparisons

This is a mechanical change addressing the various sign comparison warnings that
are identified by both clang and gcc.  This helps cleanup some of the warning
spew that occurs during builds.

llvm-svn: 205390
diff --git a/lldb/source/Core/Opcode.cpp b/lldb/source/Core/Opcode.cpp
index 2bf7f5e..73f5f85 100644
--- a/lldb/source/Core/Opcode.cpp
+++ b/lldb/source/Core/Opcode.cpp
@@ -63,7 +63,7 @@
 
     // Add spaces to make sure bytes dispay comes out even in case opcodes
     // aren't all the same size
-    if (bytes_written < min_byte_width)
+    if (static_cast<uint32_t>(bytes_written) < min_byte_width)
         bytes_written = s->Printf ("%*s", min_byte_width - bytes_written, "");
     return bytes_written;
 }