Do proper endian conversions

This fixes all testsuite failures on big endian hosts.

include/nlohmann/detail/input/binary_reader.hpp

@@ -1853,7 +1853,7 @@ class binary_reader
             }
 
             // reverse byte order prior to conversion if necessary
-            if (is_little_endian && !InputIsLittleEndian)
+            if (is_little_endian != InputIsLittleEndian)
             {
                 vec[sizeof(NumberType) - i - 1] = static_cast<uint8_t>(current);
             }