[Mips] Move MipsGOTPass implementation to the separate file.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@198783 91177308-0d34-0410-b5e6-96231b3b80d8
[Mips] Rename some classes to skip redundant mentioning of 'mips'.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@198784 91177308-0d34-0410-b5e6-96231b3b80d8
[Mips] Do not save GOT headers atoms into the RelocationPass class
fields.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@198785 91177308-0d34-0410-b5e6-96231b3b80d8
[Mips] Rename function to better reflect its purpose.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@198786 91177308-0d34-0410-b5e6-96231b3b80d8
[Mips] Do not use standard relocation identifier R_MIPS_NONE for
internal purpose. Use special LLD_R_MIPS_GLOBAL_GOT constant for that.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@198787 91177308-0d34-0410-b5e6-96231b3b80d8
[Mips] Factor out the code determines type of GOT entry (local/global)
into the separate function.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@198788 91177308-0d34-0410-b5e6-96231b3b80d8
[Mips] Add assert to check that we handle all paired relocations.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@198789 91177308-0d34-0410-b5e6-96231b3b80d8
[Mips] GOT16 relocation against non-local symbol does not require a
paired LO16 relocation.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@198790 91177308-0d34-0410-b5e6-96231b3b80d8