LoongArch: Fix bad reloc with mixed visibility ifunc symbols in shared libraries

LoongArch: Fix bad reloc with mixed visibility ifunc symbols in shared libraries

With a simple test case:

    .globl  ifunc
    .globl  ifunc_hidden
    .hidden ifunc_hidden
    .type   ifunc, %gnu_indirect_function
    .type   ifunc_hidden, %gnu_indirect_function

    .text
    .align  2
    ifunc:  ret
    ifunc_hidden: ret

    test:
      bl ifunc
      bl ifunc_hidden

"ld -shared" produces a shared object with one R_LARCH_NONE (instead of
R_LARCH_JUMP_SLOT as we expect) to relocate the GOT entry of "ifunc".
It's because the indices in .plt and .rela.plt mismatches for
STV_DEFAULT STT_IFUNC symbols when another PLT entry exists for a
STV_HIDDEN STT_IFUNC symbol, and such a mismatch breaks the logic of
loongarch_elf_finish_dynamic_symbol.  Fix the issue by reordering .plt
so the indices no longer mismatch.

Signed-off-by: Xi Ruoyao <xry111@xry111.site>