[libcpu] Sconscript: fix spell srror.
@@ -4,7 +4,7 @@ from building import *
comm = rtconfig.ARCH + '/common'
path = rtconfig.ARCH + '/' + rtconfig.CPU
-AFLAGS = ''
+ASFLAGS = ''
# The set of source files associated with this SConscript file.
if rtconfig.PLATFORM == 'armcc':
