library: extend thread safety to more static variables

library: extend thread safety to more static variables

In the commit referenced below, a '__thread' attribute
was added to numerous static variables to protect them
from concurrent access conflicts with multi-threading.

Unfortunately, that patch did not go quite far enough.

So, this commit adds a few more '__thread' qualifiers.

Reference(s):
commit 23cfb7136636f2d522b31417892de79b011ad3e4

Signed-off-by: Jim Warner <james.warner@comcast.net>