Fix build of boost-libs in NetBSD/macppc: 'char' is not signed, so a piece
of code was raising warnings and failing to build.  Changed to use 255 for
error conditions instead of -1, along with unsigned chars unconditionally.


(jmmv)

$NetBSD: patch-af,v 1.8 2011/10/14 01:12:06 jmmv Exp $

A 'char' cannot be expected to be signed.  PowerPC, for example, defines
the 'char' type as unsigned.  Fix this piece of code to not deal with
signed characters.

--- ./boost/archive/iterators/binary_from_base64.hpp.orig	2011-10-13 23:56:25.000000000 +0000
+++ ./boost/archive/iterators/binary_from_base64.hpp
@@ -39,28 +39,28 @@ template<class CharType>
 struct to_6_bit {
     typedef CharType result_type;
     CharType operator()(CharType t) const{
-        const char lookup_table[] = {
-            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,62,-1,-1,-1,63,
-            52,53,54,55,56,57,58,59,60,61,-1,-1,-1,-1,-1,-1,
-            -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,
-            15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,
-            -1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,
-            41,42,43,44,45,46,47,48,49,50,51,-1,-1,-1,-1,-1
+        unsigned char lookup_table[] = {
+            255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
+            255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
+            255,255,255,255,255,255,255,255,255,255,255,62,255,255,255,63,
+            52,53,54,55,56,57,58,59,60,61,255,255,255,255,255,255,
+            255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,
+            15,16,17,18,19,20,21,22,23,24,25,255,255,255,255,255,
+            255,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,
+            41,42,43,44,45,46,47,48,49,50,51,255,255,255,255,255
         };
         // metrowerks trips this assertion - how come?
         #if ! defined(__MWERKS__)
         BOOST_STATIC_ASSERT(128 == sizeof(lookup_table));
         #endif
-        signed char value = -1;
+        unsigned char value = 255;
         if((unsigned)t <= 127)
             value = lookup_table[(unsigned)t];
-        if(-1 == value)
+        if(255 == value)
             boost::serialization::throw_exception(
                 dataflow_exception(dataflow_exception::invalid_base64_character)
             );
-        return value;
+        return static_cast< CharType >(value);
     }
 };