Fixed off-by-one error in 'name' of add_note() function.

Previously, when assigning 'name' as a string, it's length was specified
using the full length of 'namesz'. However, this length includes the
trailing '\0' of the underlying char[]. This ultimately causes the C++
string that is created to (incorrectly) contain the '\0' character as
well. This leads to problems where e.g. the following will return false,
even when 'name' itself actually contains the string "GNU\0":

  if (name == "GNU") {
    return true;
  }
  return false;

To fix this, we should only include the length of the string minus the
trailing '\0'.

elfio/elfio_note.hpp

@@ -66,7 +66,7 @@ class note_section_accessor
              namesz + descSize > max_name_size ) {
             return false;
         }
-        name.assign( pData + 3 * sizeof( Elf_Word ), namesz );
+        name.assign( pData + 3 * sizeof( Elf_Word ), namesz - 1);
         if ( 0 == descSize ) {
             desc = 0;
         }