Make fixes and improvements

- Introduce __assert_disable global
- Improve strsignal() thread safety
- Make system call tracing thread safe
- Fix SO_RCVTIMEO / SO_SNDTIMEO on Windows
- Refactor DescribeFoo() functions into one place
- Fix fork() on Windows when TLS and MAP_STACK exist
- Round upwards in setsockopt(SO_RCVTIMEO) on Windows
- Disable futexes on OpenBSD which seem extremely broken
- Implement a better kludge for monotonic time on Windows

third_party/make/make.mk

@@ -62,7 +62,6 @@ THIRD_PARTY_MAKE_SRCS_BASE =				\
 	third_party/make/remake.c			\
 	third_party/make/remote-stub.c			\
 	third_party/make/rule.c				\
-	third_party/make/signame.c			\
 	third_party/make/strcache.c			\
 	third_party/make/variable.c			\
 	third_party/make/version.c			\