Move oniguruma and decNumber to vendor directory (#3234)

vendor/decNumber/example8.c

@@ -0,0 +1,39 @@
+/* ------------------------------------------------------------------ */
+/* Decimal Number Library Demonstration program                       */
+/* ------------------------------------------------------------------ */
+/* Copyright (c) IBM Corporation, 2001, 2007.  All rights reserved.   */
+/* ----------------------------------------------------------------+- */
+/*                                                 right margin -->|  */
+
+// example8.c -- using decQuad with the decNumber module
+
+// compile: example8.c decContext.c decQuad.c
+//     and: decNumber.c decimal128.c decimal64.c
+
+#include "decQuad.h"               // decQuad library
+#include "decimal128.h"            // interface to decNumber
+#include <stdio.h>                 // for printf
+
+int main(int argc, char *argv[]) {
+  decQuad a;                       // working decQuad
+  decNumber numa, numb;            // working decNumbers
+  decContext set;                  // working context
+  char string[DECQUAD_String];     // number->string buffer
+
+  if (argc<3) {                    // not enough words
+    printf("Please supply two numbers for power(2*a, b).\n");
+    return 1;
+    }
+  decContextDefault(&set, DEC_INIT_DECQUAD); // initialize
+
+  decQuadFromString(&a, argv[1], &set);      // get a
+  decQuadAdd(&a, &a, &a, &set);              // double a
+  decQuadToNumber(&a, &numa);                // convert to decNumber
+  decNumberFromString(&numb, argv[2], &set);
+  decNumberPower(&numa, &numa, &numb, &set); // numa=numa**numb
+  decQuadFromNumber(&a, &numa, &set);        // back via a Quad
+  decQuadToString(&a, string);               // ..
+
+  printf("power(2*%s, %s) => %s\n", argv[1], argv[2], string);
+  return 0;
+  } // main