[Mips] Add MipsPat `(MipsGPRel tglobaladdr:$in)` to select MipsISD::GPRel TargetGlobalAddress (#165531)

The original logic:
```
SelectionDAG has 17 nodes:
  t0: ch,glue = EntryToken
          t2: i64,ch = CopyFromReg t0, Register:i64 %0
        t11: i32 = truncate t2
      t14: i32 = and t11, Constant:i32<1>
        t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3]
      t21: i64 = add Register:i64 $gp_64, t20
        t16: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str> 0 [TF=3]
      t18: i64 = add Register:i64 $gp_64, t16
    t7: i64 = select t14, t21, t18
```

When SelectionDAG process visitSELECT, would fold select(cond,
binop(x, y), binop(x, z)) to binop(x, select(cond, y, z)).
As follows:
```
SelectionDAG has 16 nodes:
  t0: ch,glue = EntryToken
            t2: i64,ch = CopyFromReg t0, Register:i64 %0
          t11: i32 = truncate t2
        t14: i32 = and t11, Constant:i32<1>
        t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3]
        t16: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str> 0 [TF=3]
      t22: i64 = select t14, t20, t16
    t23: i64 = add Register:i64 $gp_64, t22
```

Therefore, the original MipsPat `add GPR64:$gp, (MipsGPRel
tglobaladdr:$in)` is no longer available. And there would be an assert:
```
ISEL: Starting selection on root node: t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3]
ISEL: Starting pattern match
  Initial Opcode index to 0
  Match failed at index 0
LLVM ERROR: Cannot select: t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3]
```

So we add a new MipsPat `def : MipsPat<(MipsGPRel tglobaladdr:$in),
              (DADDiu ZERO_64, tglobaladdr:$in)>, ISA_MIPS3, ABI_N64;`
to parse MipsISD::GPRel TargetGlobalAddress.


Fix #142060.