Abstractions to compile systemlib for Linux and Nuttx

Modified uint32_t casts of pointers to unsigned long for portability.
It otherwise breaks on x86_64.

Added _PX4_IOC to handle the conflice between _IOC on Linux and NuttX.

Removed use of px4::ok() because it cannot be used in a thread based
implementation. Changed to use px4::AppMgr which uses ok() on ROS.

Removed up_cxxinitialize.c from Linux build.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

src/modules/systemlib/module.mk

@@ -43,7 +43,6 @@ SRCS		 = err.c \
 		   conversions.c \
 		   cpuload.c \
 		   getopt_long.c \
-		   up_cxxinitialize.c \
 		   pid/pid.c \
 		   systemlib.c \
 		   airspeed.c \
@@ -57,6 +56,10 @@ SRCS		 = err.c \
 		   circuit_breaker_params.c \
 		   mcu_version.c
 
+ifeq ($(PX4_TARGET_OS),nuttx)
+SRCS		+= up_cxxinitialize.c 
+endif
+
 MAXOPTIMIZATION	 = -Os
 
 EXTRACFLAGS	= -Wno-sign-compare