[libc][stdlib] Add calloc header (#94403)

Author: PiJoules

libc/src/stdlib/calloc.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for calloc ------------------------*- C++ -*-===//
+//
+// 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 <stddef.h>
+
+#ifndef LLVM_LIBC_SRC_STDLIB_CALLOC_H
+#define LLVM_LIBC_SRC_STDLIB_CALLOC_H
+
+namespace LIBC_NAMESPACE {
+
+void *calloc(size_t num, size_t size);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDLIB_CALLOC_H