[Mips] Do not hard-code the paired relocation type
[Mips] Do not hard-code the paired relocation type

Request `getPairRelocation()` function to get paired relocation type.
That allows us to look up another pairs like R_MICROMIPS_HI16/LO16
in the future.

git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@221539 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld