ART: Use initial-exec TLS mode for Thread TLS

Avoid unnecessary overhead. This works as on the host we do not
run complicated workloads with other libraries etc, so glibc's
preallocated storage is large enough to fit this.

Bug: 138329277
Test: m test-art-host
Change-Id: Ibd013521b7fc043b62ed79a72e94c0c002c7c402
1 file changed