MIPSR6: Fix compilation failure due to missing instruction patching

On MIPS32R6, instruction JIC and JIALC where not properly
patched and this caused compilation failure in snapshot
generating phase

Change-Id: I29d8323faf22f825116e295cd2a2d55e714e61ed
Reviewed-on: https://chromium-review.googlesource.com/c/1314118Reviewed-by: Sreten Kovacevic <skovacevic@wavecomp.com>
Commit-Queue: Ivica Bogosavljevic <ibogosavljevic@wavecomp.com>
Cr-Commit-Position: refs/heads/master@{#57216}

src/mips/assembler-mips-inl.h

@@ -281,12 +281,13 @@ Handle<Code> Assembler::relative_code_target_object_handle_at(
     Address pc) const {
   Instr instr1 = instr_at(pc);
   Instr instr2 = instr_at(pc + kInstrSize);
+  DCHECK(IsLui(instr1));
+  DCHECK(IsOri(instr2) || IsNal(instr2));
+  DCHECK(IsNal(instr2) || IsNal(instr_at(pc - kInstrSize)));
   if (IsNal(instr2)) {
     instr2 = instr_at(pc + 2 * kInstrSize);
   }
   // Interpret 2 instructions generated by li (lui/ori).
-  DCHECK(IsLui(instr1));
-  DCHECK(IsOri(instr2));
   int code_target_index = GetLuiOriImmediate(instr1, instr2);
   return GetCodeTarget(code_target_index);
 }

src/mips/assembler-mips.cc

@@ -4104,6 +4104,8 @@ void Assembler::set_target_value_at(Address pc, uint32_t target,
     instr1 |= lui_offset;
     instr2 |= jic_offset;
 
+    instr_at_put(pc, instr1);
+    instr_at_put(pc + kInstrSize, instr2);
   } else {
     Instr instr3 = instr_at(pc + 2 * kInstrSize);
     // If we are using relative calls/jumps for builtins.