Expose __set_errno through libdsyscalls

This allows libhybris to override the function and pass
errno changes from system calls from bionic to glibc.

Change-Id: If9575592fdfcedd783a1d247d47b8d9e00a2d780
Re-assign well-known TLS slots

Avoid bionic overwriting existing glibc TLS field values.

Change-Id: I20b88ce74104dbf8e159a9b6d6a42c67f13d391b
log -> alog

Change-Id: Id6f69450f47251b5d849d92231b5882affc3c57f