Fix reference to out of scope local in adb_thread_setname.

Bug: 67320882
Bug: https://android-review.googlesource.com/#/c/168725/5/adb/sysdeps.h@639


Test: boots, adbd thread names look sane
Signed-off-by: Ivan Maidanski <i.maidanski@samsung.com>
Change-Id: Ib3bdf53658f3903de8f0a5688f7d77745e677c77
(cherry picked from commit 7462f185)