Fix 2 "Condition is always true" compiler warnings.

tinyxml2.cpp

@@ -471,7 +471,7 @@ const char* XMLUtil::GetCharacterRef( const char* p, char* value, int* length )
                 else {
                     return 0;
                 }
-                TIXMLASSERT( digit >= 0 && digit < 16);
+                TIXMLASSERT( digit < 16 );
                 TIXMLASSERT( digit == 0 || mult <= UINT_MAX / digit );
                 const unsigned int digitScaled = mult * digit;
                 TIXMLASSERT( ucs <= ULONG_MAX - digitScaled );
@@ -501,7 +501,7 @@ const char* XMLUtil::GetCharacterRef( const char* p, char* value, int* length )
             while ( *q != '#' ) {
                 if ( *q >= '0' && *q <= '9' ) {
                     const unsigned int digit = *q - '0';
-                    TIXMLASSERT( digit >= 0 && digit < 10);
+                    TIXMLASSERT( digit < 10 );
                     TIXMLASSERT( digit == 0 || mult <= UINT_MAX / digit );
                     const unsigned int digitScaled = mult * digit;
                     TIXMLASSERT( ucs <= ULONG_MAX - digitScaled );