refactor: 将quick_exit替换为_Exit以提高代码一致性

src/2/P1223.cpp

@@ -25,5 +25,5 @@ int main(){
         nowWait+=a[i].first;
     }
     std::cout<<std::fixed<<std::setprecision(2)<<'\n'<<(double(sumWait)/double(n))<<'\n'<<std::flush;
-    quick_exit(0);
+    _Exit(0);
 }

src/2/P1962.cpp

@@ -83,5 +83,5 @@ int main(){
     base[0][1]=base[1][0]=base[1][1] = 1;
     base = fp(base,n);
     std::cout<<(base[0][1]+base[1][1])%p<<'\n'<<std::flush;
-    quick_exit(0);
+    _Exit(0);
 }

src/2/P2719.cpp

@@ -25,5 +25,5 @@ int main(){
     
     std::cout<<std::fixed<<std::setprecision(4)<<dp[n][n]<<'\n';
     std::flush(std::cout);
-    quick_exit(0);
+    _Exit(0);
 }