[BOLT] Bugfix: use getFirstNonPseudo() instead of begin()

RA states are only assigned to non-pseudo instructions. Because of this,
CFI instructions are skipped.
Here, I incorrectly used begin(), not skipping CFIs.

Author: bgergely0

bolt/lib/Passes/InsertNegateRAStatePass.cpp

@@ -91,15 +91,16 @@ void InsertNegateRAState::coverFunctionFragmentStart(BinaryFunction &BF,
       });
   // If a function is already split in the input, the first FF can also start
   // with Signed state. This covers that scenario as well.
-  auto RAState = BC.MIB->getRAState(*(*FirstNonEmpty)->begin());
+  auto II = (*FirstNonEmpty)->getFirstNonPseudo();
+  auto RAState = BC.MIB->getRAState(*II);
   if (!RAState) {
     BC.errs() << "BOLT-ERROR: unknown RAState after inferUnknownStates "
               << " in function " << BF.getPrintName() << "\n";
     PassFailed = true;
     return;
   }
   if (*RAState)
-    BF.addCFIInstruction(*FirstNonEmpty, (*FirstNonEmpty)->begin(),
+    BF.addCFIInstruction(*FirstNonEmpty, II,
                          MCCFIInstruction::createNegateRAState(nullptr));
 }