addrenv interface changes: up_addrenv_create() may need to create .text and...

addrenv interface changes: up_addrenv_create() may need to create .text and .bss/.data separately because of differing access privileges (read/execute vs read/write).  And, as a consequence, up_addrenv_vaddr() needs to be split into up_addrenv_vtext(0 and up_addrenv_vdata().