libiscsi is usually linked by QEMU, and QEMU sets thread proc name
by function. But iser cm thread is created by libiscsi privately,
QEMU can't set this thread. After attaching a iser disk, we can find
a new thread 'qemu-system-x86' in QEMU process.
With this patch, iser cm thread works with thread name
'iscsi_cm_thread'.
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>