regedit: Correctly export hex values with no data.

programs/regedit/regproc.c

@@ -1300,6 +1300,8 @@ static void export_hex_data(FILE *fp, WCHAR **buf, DWORD type, DWORD line_len,
 
     line_len += export_hex_data_type(fp, type, unicode);
 
+    if (!size) return;
+
     if (!unicode && (type == REG_EXPAND_SZ || type == REG_MULTI_SZ))
         data = GetMultiByteStringN(data, size / sizeof(WCHAR), &size);
 
@@ -1354,8 +1356,12 @@ static void export_data(FILE *fp, WCHAR *value_name, DWORD value_len, DWORD type
         break;
     }
 
+    if (size || type == REG_SZ)
+    {
         REGPROC_write_line(fp, buf, unicode);
         heap_free(buf);
+    }
+
     export_newline(fp, unicode);
 }