[Refactor] Rename scriptPubKey -> exec_script

Rename misleading scriptPubKey in ExecuteWitnessScript() function to
correctly relfect what is being executed.

Author: sanket1729

src/script/interpreter.cpp

@@ -1807,16 +1807,16 @@ bool GenericTransactionSignatureChecker<T>::CheckSequence(const CScriptNum& nSeq
 template class GenericTransactionSignatureChecker<CTransaction>;
 template class GenericTransactionSignatureChecker<CMutableTransaction>;
 
-static bool ExecuteWitnessScript(const Span<const valtype>& stack_span, const CScript& scriptPubKey, unsigned int flags, SigVersion sigversion, const BaseSignatureChecker& checker, ScriptExecutionData& execdata, ScriptError* serror)
+static bool ExecuteWitnessScript(const Span<const valtype>& stack_span, const CScript& exec_script, unsigned int flags, SigVersion sigversion, const BaseSignatureChecker& checker, ScriptExecutionData& execdata, ScriptError* serror)
 {
     std::vector<valtype> stack{stack_span.begin(), stack_span.end()};
 
     if (sigversion == SigVersion::TAPSCRIPT) {
         // OP_SUCCESSx processing overrides everything, including stack element size limits
-        CScript::const_iterator pc = scriptPubKey.begin();
-        while (pc < scriptPubKey.end()) {
+        CScript::const_iterator pc = exec_script.begin();
+        while (pc < exec_script.end()) {
             opcodetype opcode;
-            if (!scriptPubKey.GetOp(pc, opcode)) {
+            if (!exec_script.GetOp(pc, opcode)) {
                 // Note how this condition would not be reached if an unknown OP_SUCCESSx was found
                 return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
             }
@@ -1839,7 +1839,7 @@ static bool ExecuteWitnessScript(const Span<const valtype>& stack_span, const CS
     }
 
     // Run the script interpreter.
-    if (!EvalScript(stack, scriptPubKey, flags, checker, sigversion, execdata, serror)) return false;
+    if (!EvalScript(stack, exec_script, flags, checker, sigversion, execdata, serror)) return false;
 
     // Scripts inside witness implicitly require cleanstack behaviour
     if (stack.size() != 1) return set_error(serror, SCRIPT_ERR_CLEANSTACK);