LoongArch: ld: Add support for linker relaxation.
Add ld relax support and testsuits.
ld/ChangeLog:
* emultempl/loongarchelf.em: Regenerated.
* testsuite/ld-elf/compressed1d.d: Xfail loongarch*-*.
* testsuite/ld-elf/pr26936.d: Likewise.
* testsuite/ld-loongarch-elf/disas-jirl.d: Regenerated.
* testsuite/ld-loongarch-elf/disas-jirl-32.d: Regenerated.
* testsuite/ld-loongarch-elf/jmp_op.d: Likewise.
* testsuite/ld-loongarch-elf/macro_op.d: Likewise.
* testsuite/ld-loongarch-elf/macro_op_32.d: Likewise.
* testsuite/ld-loongarch-elf/relax-align.dd: New test.
* testsuite/ld-loongarch-elf/relax-align.s: New test.
* testsuite/ld-loongarch-elf/relax.exp: New test.
* testsuite/ld-loongarch-elf/relax.s: New test.
* testsuite/ld-loongarch-elf/uleb128.dd: New test.
* testsuite/ld-loongarch-elf/uleb128.s: New test.