This makes ucontext.h related discovery functions work.
elseif(CMAKE_SYSTEM_NAME STREQUAL SunOS)
set(CMAKE_REQUIRED_INCLUDES /opt/local/include)
endif()
-if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin AND NOT CMAKE_SYSTEM_NAME STREQUAL FreeBSD)
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin AND NOT CMAKE_SYSTEM_NAME STREQUAL FreeBSD AND NOT CMAKE_SYSTEM_NAME STREQUAL NetBSD)
set(CMAKE_REQUIRED_DEFINITIONS "-D_DEFAULT_SOURCE -D_POSIX_C_SOURCE=200809L")
endif()