platforms: use define for lockstep scheduler

Instead of using the define __PX4_POSIX_SITL it makes more sense to have
a define just to determine if the lockstep scheduler should be used.

platforms/posix/src/CMakeLists.txt

@@ -31,7 +31,7 @@
 #
 ############################################################################
 
-if (LOCKSTEP_SCHEDULER_NEEDED)
+if (ENABLE_LOCKSTEP_SCHEDULER)
 	add_subdirectory(lockstep_scheduler)
 endif()
 

platforms/posix/src/px4_layer/CMakeLists.txt

@@ -56,7 +56,7 @@ target_compile_definitions(px4_layer PRIVATE MODULE_NAME="px4")
 target_link_libraries(px4_layer PRIVATE work_queue)
 target_link_libraries(px4_layer PRIVATE px4_daemon)
 
-if(LOCKSTEP_SCHEDULER_NEEDED)
+if(ENABLE_LOCKSTEP_SCHEDULER)
 	target_link_libraries(px4_layer PRIVATE lockstep_scheduler)
 	include_directories(${PX4_SOURCE_DIR}/platforms/posix/src/lockstep_scheduler/include)
 endif()

platforms/posix/src/px4_layer/drv_hrt.cpp

@@ -49,7 +49,7 @@
 #include <errno.h>
 #include "hrt_work.h"
 
-#if defined(__PX4_POSIX_SITL)
+#if defined(ENABLE_LOCKSTEP_SCHEDULER)
 #include <lockstep_scheduler/lockstep_scheduler.h>
 #endif
 
@@ -72,7 +72,7 @@ static hrt_abstime _delay_interval = 0;
 static hrt_abstime max_time = 0;
 static pthread_mutex_t _hrt_mutex = PTHREAD_MUTEX_INITIALIZER;
 
-#if defined(__PX4_POSIX_SITL)
+#if defined(ENABLE_LOCKSTEP_SCHEDULER)
 static LockstepScheduler lockstep_scheduler;
 #endif
 
@@ -594,7 +594,7 @@ void abstime_to_ts(struct timespec *ts, hrt_abstime abstime)
 	ts->tv_nsec = abstime * 1000;
 }
 
-#if defined(__PX4_POSIX_SITL)
+#if defined(ENABLE_LOCKSTEP_SCHEDULER)
 int px4_clock_gettime(clockid_t clk_id, struct timespec *tp)
 {
 	if (clk_id == CLOCK_MONOTONIC) {