adb: avoid freeing argv entries on Windows.

We assign string literals directly to argv[0], which leads to fun
explosions when we attempt to free  when the runtime can detect that
a bad free happened, which seems to happen reliably with lld.

Bug: http://b/110800681
Test: `adb shell true` on windows
Change-Id: Ica81e472c31686d80b58c41ff6d2b825baef06fb