[build] remove hard coded path issue in SConscript

components/external/cairo/SConscript

-Import('RTT_ROOT')
-Import('rtconfig')
-
 from building import *
 import os
 
 CAIRO_VERSION = '1.10.2'
 CAIRO_PATH = 'cairo-' + CAIRO_VERSION
+cwd = GetCurrentDir()
 
 if GetDepend('RT_USING_CAIRO') and not os.path.exists(CAIRO_PATH):
     print '================ERROR============================'
@@ -99,7 +97,7 @@ cairo.c
 for item in range(len(src)):
     src[item] = CAIRO_PATH + '/src/' + src[item]
 
-CPPPATH = [RTT_ROOT + '/components/external/cairo/' + CAIRO_PATH + '/src', RTT_ROOT + '/components/external/cairo/']
+CPPPATH = [cwd + '/' + CAIRO_PATH + '/src', cwd]
 group = DefineGroup('cairo', src, depend = ['RT_USING_CAIRO', 'RT_USING_NEWLIB', 'RTGUI_IMAGE_PNG', 'RT_USING_PTHREADS'], CPPPATH = CPPPATH)
 
 Return('group')

components/external/lzo/SConscript

-Import('RTT_ROOT')
-Import('rtconfig')
 from building import *
 
+cwd = GetCurrentDir()
 src	= Split('''
 minilzo.c
 lzo.c
 ''')
-CPPPATH = [RTT_ROOT + '/components/external/lzo']
+CPPPATH = [cwd]
 
 group = DefineGroup('lzo', src, depend = ['RT_USING_LZO'], CPPPATH = CPPPATH)
 

components/external/nanopb/SConscript

-Import('RTT_ROOT')
-Import('rtconfig')
 from building import *
 
+cwd = GetCurrentDir()
 src	= Split('''
 pb_common.c
 pb_decode.c
 pb_encode.c
 ''')
-CPPPATH = [RTT_ROOT + '/components/external/nanopb']
+CPPPATH = [cwd]
 
 group = DefineGroup('Nanopb', src, depend = ['RT_USING_NANOPB'], CPPPATH = CPPPATH)
 

components/net/SConscript

@@ -4,14 +4,15 @@ Import('RTT_ROOT')
 from building import *
 
 objs = []
-list = os.listdir(os.path.join(RTT_ROOT, 'components', 'net'))
+cwd = GetCurrentDir()
+list = os.listdir(cwd)
 
 # the default version of LWIP is 1.4.1
 if not GetDepend('RT_USING_LWIP132') and not GetDepend('RT_USING_LWIP140') and not GetDepend('RT_USING_LWIP_HEAD'):
     AddDepend('RT_USING_LWIP141')
 
 for d in list:
-    path = os.path.join(RTT_ROOT, 'components', 'net', d)
+    path = os.path.join(cwd, d)
     if os.path.isfile(os.path.join(path, 'SConscript')):
         objs = objs + SConscript(os.path.join(d, 'SConscript'))