MIPS: Fix unbounded label counter.

src/mips64/assembler-mips64.h

Index: src/mips64/assembler-mips64.h
diff --git a/src/mips64/assembler-mips64.h b/src/mips64/assembler-mips64.h
index 6636d2b94a22e39c499fe1decd4cc50cbd523110..2281be2df924043dfc3bbf8452523567306cf2fe 100644
--- a/src/mips64/assembler-mips64.h
+++ b/src/mips64/assembler-mips64.h
@@ -1215,6 +1215,8 @@ class Assembler : public AssemblerBase {
 
   bool IsPrevInstrCompactBranch() { return prev_instr_compact_branch_; }
 
+  inline int UnboundLabelsCount() { return unbound_labels_count_; }
+
  protected:
   // Load Scaled Address instructions.
   void lsa(Register rd, Register rt, Register rs, uint8_t sa);