(ASM_FILE_START_1): Always output .noopt because /bin/as is buggy.
Added #undef to {INIT,FINI,CTORS,DTORS}_SECTION_ASM_OP, ... when
not using GAS.
(CONST_SECTION_FUNCTION): Override svr3 default.
(EXTRA_SECTION_FUNCTIONS): Override svr3 default.
(OBJECT_FORMAT_COFF): Added define for collect2.
(MY_ISCOFF): For collect2 to handle aix and svr3 object file.

From-SVN: r4687