threads: follow formatting rules

Adjust long lines and correct padding in preprocessor lines to
match the formatting rules

Signed-off-by: Georgi Valkov <gvalkov@gmail.com>

Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24941)