Use arrays on stack and avoid use of new and delete operators.

[sivachandra]

Summary

Also fix an error found with LLVM_USE_SANITIZER=Address.

libc/src/string/strcat/strcat_test.cpp

 //===---------------------- Unittests for strcat --------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include <string>
 
 #include "src/string/strcat/strcat.h"
 #include "gtest/gtest.h"
 
 TEST(StrCatTest, EmptyDest) {
   std::string abc = "abc";
-  char *dest = new char[4];
+  char dest[4];
 
   dest[0] = '\0';
 
   char *result = __llvm_libc::strcat(dest, abc.c_str());
   ASSERT_EQ(dest, result);
   ASSERT_EQ(std::string(dest), abc);
   ASSERT_EQ(std::string(dest).size(), abc.size());
-
-  delete[] dest;
 }
 
 TEST(StrCatTest, NonEmptyDest) {
   std::string abc = "abc";
-  char *dest = new char[4];
+  char dest[7];
 
   dest[0] = 'x';
   dest[1] = 'y';
   dest[2] = 'z';
   dest[3] = '\0';
 
   char *result = __llvm_libc::strcat(dest, abc.c_str());
   ASSERT_EQ(dest, result);
   ASSERT_EQ(std::string(dest), std::string("xyz") + abc);
   ASSERT_EQ(std::string(dest).size(), abc.size() + 3);
-
-  delete[] dest;
 }

libc/src/string/strcpy/strcpy_test.cpp

 //===----------------------- Unittests for strcpy -------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include <string>
 
 #include "src/string/strcpy/strcpy.h"
 #include "gtest/gtest.h"
 
 TEST(StrCpyTest, EmptyDest) {
   std::string abc = "abc";
-  char *dest = new char[4];
+  char dest[4];
 
   char *result = __llvm_libc::strcpy(dest, abc.c_str());
   ASSERT_EQ(dest, result);
   ASSERT_EQ(std::string(dest), abc);
   ASSERT_EQ(std::string(dest).size(), abc.size());
-
-  delete[] dest;
 }
 
 TEST(StrCpyTest, OffsetDest) {
   std::string abc = "abc";
-  char *dest = new char[7];
+  char dest[7];
 
   dest[0] = 'x';
   dest[1] = 'y';
   dest[2] = 'z';
 
   char *result = __llvm_libc::strcpy(dest + 3, abc.c_str());
   ASSERT_EQ(dest + 3, result);
   ASSERT_EQ(std::string(dest), std::string("xyz") + abc);
   ASSERT_EQ(std::string(dest).size(), abc.size() + 3);
-
-  delete[] dest;
 }