Fix build errors

Fix build errors

-Wno-error=unused-result is applied to tests/logger since it's a test module.

[  160s] logger.c: In function 'dump_logger':
[  160s] logger.c:33:27: error: initialization of 'struct logger_entry *'
from incompatible pointer type 'char *' [-Werror=incompatible-pointer-types]
[  160s]    33 |  struct logger_entry *e = buf;
...
[  160s] logger.c: In function 'tstart':
[  160s] logger.c:24:2: error: ignoring return value of 'write', declared with
attribute warn_unused_result [-Werror=unused-result]
[  160s]    24 |  write(*fd, "child thread msg #1\nchild thread msg #2", 39);
[  160s]       |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...

Change-Id: I1496c7591031e3c61c3b3646712d641bdbdbdfe9
Signed-off-by: Hyotaek Shim <hyotaek.shim@samsung.com>