The .except, .loader and .typchk are not mapped to memory,
so do not set their SEC_ALLOC flag.
bfd/ChangeLog:
* coffcode.h (styp_to_sec_flags) [RS6000COFF_C]: Add handling
of STYP_EXCEPT, STYP_LOADER and STYP_TYPCHK sections.
ld/testsuite/ChangeLog:
* ld-powerpc/aix-core-sec-1.hd, ld-powerpc/aix-core-sec-2.hd,
ld-powerpc/aix-core-sec-3.hd: Adjust expected section flags
for section .loader.