linux-user: Adjust brk for load_bias

PIE executables are usually linked at offset 0 and are
relocated somewhere during load.  The hiaddr needs to
be adjusted to keep the brk next to the executable.

Cc: qemu-stable@nongnu.org
Fixes: 1f356e8c ("linux-user: Adjust initial brk when interpreter is close to executable")
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>