wscript: prepend default CFLAGS values
wscript: prepend default CFLAGS values

Use default CFLAGS while still allowing CFLAGS to be overwritten from command line.

Signed-off-by: Jeppe Ledet-Pedersen <04ca46c996f3ce83ad557eea1980ca8ca065ba1b@ledets.dk>
marshall/libcsp,pacheco017/libcsp,kubostech/KubOS,marshall/libcsp,pacheco017/libcsp,satlab/libcsp,libcsp/libcsp,Psykar/kubos,satlab/libcsp,kubostech/KubOS,marshall/libcsp,GomSpace/libcsp,satlab/libcsp,Psykar/kubos,Psykar/kubos,Psykar/kubos,Psykar/kubos,GomSpace/libcsp,pacheco017/libcsp,pacheco017/libcsp,Psykar/kubos,Psykar/kubos,GomSpace/libcsp,libcsp/libcsp