[FL-2052] New build system based on scons (#1269)

lib/freertos.scons

@@ -0,0 +1,28 @@
+Import("env")
+
+env.Append(
+    CPPPATH=[
+        "#/lib/drivers",
+        "#/lib/FreeRTOS-Kernel/include",
+        "#/lib/FreeRTOS-Kernel/portable/GCC/ARM_CM4F",
+        "#/lib/FreeRTOS-glue",
+    ],
+    CPPDEFINES=[
+        "HAVE_FREERTOS",
+    ],
+)
+
+
+libenv = env.Clone(FW_LIB_NAME="freertos")
+libenv.ApplyLibFlags()
+
+
+sources = libenv.Glob("FreeRTOS-Kernel/*.c", source=True)
+sources += [
+    "FreeRTOS-Kernel/portable/GCC/ARM_CM4F/port.c",
+    "FreeRTOS-glue/cmsis_os2.c",
+]
+
+lib = libenv.StaticLibrary("${FW_LIB_NAME}", sources)
+libenv.Install("${LIB_DIST_DIR}", lib)
+Return("lib")