[Mips] Simplify calculations of relocations - replace scatterBits calls
by bitwise AND operator and remove redundant local variables.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@199554 91177308-0d34-0410-b5e6-96231b3b80d8
[Mips] Emit ELF header for MIPS target. ELF flags set is mostly hardcoded.
Later we need to improve that solution and build a correct set of flags
by merging ELF flags from all input objects.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@199555 91177308-0d34-0410-b5e6-96231b3b80d8
[Mips] Use explicit assembler instructions in the tests.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@199556 91177308-0d34-0410-b5e6-96231b3b80d8