POSIX: Added PX4_ROOTFSDIR to file paths

Set a default path relative to current dir for the posix target.

Running make posixrun will create the required directoroes and then run
mainapp from its build location.

PX4_ROOTFSDIR is set to nothing for nuttx.

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

src/platforms/px4_defines.h

@@ -92,6 +92,8 @@ typedef param_t px4_param_t;
  */
 #if defined(__PX4_NUTTX)
 
+#define PX4_ROOTFSDIR 
+
 /* XXX this is a hack to resolve conflicts with NuttX headers */
 #if !defined(__PX4_TESTS)
 #define isspace(c) \
@@ -136,6 +138,12 @@ __END_DECLS
 
 #define px4_statfs_buf_f_bavail_t unsigned long
 
+#if defined(__PX4_QURT)
+#define PX4_ROOTFSDIR 
+#else
+#define PX4_ROOTFSDIR "rootfs"
+#endif
+
 #endif
 
 
@@ -198,6 +206,10 @@ __END_DECLS
 #endif
 
 #if defined(__PX4_QURT)
+
+#define PX4_ROOTFSDIR 
+#define DEFAULT_PARAM_FILE "/fs/eeprom/parameters"
+
 #define SIOCDEVPRIVATE 999999
 
 // Missing math.h defines
@@ -211,7 +223,6 @@ __END_DECLS
 #define fminf(x, y) ((x) > (y) ? y : x)
 #endif
 
-
 #endif
 
 /*