[mips] Extend MipsMCExpr class to handle %higher(sym1 - sym2 + const) and
%highest(sym1 - sym2 + const) relocations. Remove "ABS_" from VK_Mips_HI
and VK_Mips_LO enums in MipsMCExpr, to be consistent with VK_Mips_HIGHER
and VK_Mips_HIGHEST.

This change also deletes test file test/MC/Mips/higher_highest.ll and moves
its CHECK's to the new test file test/MC/Mips/higher-highest-addressing.s.
The deleted file tests that R_MIPS_HIGHER and R_MIPS_HIGHEST relocations are
emitted in the .o file. Since it uses -force-mips-long-branch option, it was
created when MipsLongBranch's implementation was emitting R_MIPS_HIGHER and
R_MIPS_HIGHEST relocations in the .o file. It was disabled when MipsLongBranch
started to directly calculate offsets.

Differential Revision: http://llvm-reviews.chandlerc.com/D3230


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205522 91177308-0d34-0410-b5e6-96231b3b80d8
[ARM] When generating a vpaddl node the input lane type is not always the type of the
add operation since extract_vector_elt can perform an extend operation. Get the input lane
type from the vector on which we're performing the vpaddl operation on and extend or
truncate it to the output type of the original add node.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205523 91177308-0d34-0410-b5e6-96231b3b80d8