LoongArch: Add DT_RELR tests

Most tests are ported from AArch64.

The relr-addend test is added to make sure the addend (link-time address)
is correctly written into the relocated section.  Doing so is not
strictly needed for RELA, but strictly needed for RELR).

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