RISC-V: Handle extensions combination correctly in multilib-generator.
Input string consist of four parts:
<primary arch>-<abi>-<additional arches>-<extensions>
and generator doing combination with <extensions> part, but it just
append the extension at the end of arch string, it might generate
invalid arch.
For example, without this patch `./multilib-generator rv32imafc-ilp32--d`
will generate:
MULTILIB_OPTIONS = march=rv32imafc/march=rv32imafcd mabi=ilp32
^^^^^^^^^^
and rv32imafcd is not in canonical order.
Tested with python 2.7 and python 3.6/3.7.
gcc/ChangeLog
* gcc/config/riscv/multilib-generator: (canonical_order): New.
(arch_canonicalize): Dito.
Apply arch_canonicalize for alts.
From-SVN: r274137