linux-user: Use is_error() to avoid warnings and make the code clearer

This fixes:

  linux-user/flatload.c:740:9: warning: Loss of sign in implicit conversion
      if (res > (unsigned long)-4096)
          ^~~

Reported-by: Clang Static Analyzer
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20180604153722.24956-3-f4bug@amsat.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
1 file changed