[mips] Handle branch expansion corner cases

When potential jump instruction and target are in the same segment, use
jump instruction with immediate field.

In cases where offset does not fit immediate value of a bc/j instructions,
offset is stored into register, and then jump register instruction is used.

Differential Revision: https://reviews.llvm.org/D48019


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@339126 91177308-0d34-0410-b5e6-96231b3b80d8