Add Argon2 bundled library to crypto backend.

The Argon2i/id is a password hashing function that
won Password Hashing Competiton.

It will be (optionally) used in LUKS2 for passworrd-based
key derivation.

We have to bundle code for now (similar PBKDF2 years ago)
because there is yet no usable implementation in common
crypto libraries.
(Once there is native implementation, cryptsetup
will switch to the crypto library version.)

For now, we use reference (not optimized but portable) implementation.

This patch contains bundled Argon2 algorithm library copied from
  https://github.com/P-H-C/phc-winner-argon2

For more info see Password Hashing Competition site:
  https://password-hashing.net/
and draft of RFC document
  https://datatracker.ietf.org/doc/draft-irtf-cfrg-argon2/

Signed-off-by: Milan Broz <gmazyland@gmail.com>

lib/crypto_backend/argon2/blake2/blake2-impl.h

@@ -0,0 +1,156 @@
+/*
+ * Argon2 reference source code package - reference C implementations
+ *
+ * Copyright 2015
+ * Daniel Dinu, Dmitry Khovratovich, Jean-Philippe Aumasson, and Samuel Neves
+ *
+ * You may use this work under the terms of a Creative Commons CC0 1.0
+ * License/Waiver or the Apache Public License 2.0, at your option. The terms of
+ * these licenses can be found at:
+ *
+ * - CC0 1.0 Universal : http://creativecommons.org/publicdomain/zero/1.0
+ * - Apache 2.0        : http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * You should have received a copy of both of these licenses along with this
+ * software. If not, they may be obtained at the above URLs.
+ */
+
+#ifndef PORTABLE_BLAKE2_IMPL_H
+#define PORTABLE_BLAKE2_IMPL_H
+
+#include <stdint.h>
+#include <string.h>
+
+#if defined(_MSC_VER)
+#define BLAKE2_INLINE __inline
+#elif defined(__GNUC__) || defined(__clang__)
+#define BLAKE2_INLINE __inline__
+#else
+#define BLAKE2_INLINE
+#endif
+
+/* Argon2 Team - Begin Code */
+/*
+   Not an exhaustive list, but should cover the majority of modern platforms
+   Additionally, the code will always be correct---this is only a performance
+   tweak.
+*/
+#if (defined(__BYTE_ORDER__) &&                                                \
+     (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)) ||                           \
+    defined(__LITTLE_ENDIAN__) || defined(__ARMEL__) || defined(__MIPSEL__) || \
+    defined(__AARCH64EL__) || defined(__amd64__) || defined(__i386__) ||       \
+    defined(_M_IX86) || defined(_M_X64) || defined(_M_AMD64) ||                \
+    defined(_M_ARM)
+#define NATIVE_LITTLE_ENDIAN
+#endif
+/* Argon2 Team - End Code */
+
+static BLAKE2_INLINE uint32_t load32(const void *src) {
+#if defined(NATIVE_LITTLE_ENDIAN)
+    uint32_t w;
+    memcpy(&w, src, sizeof w);
+    return w;
+#else
+    const uint8_t *p = (const uint8_t *)src;
+    uint32_t w = *p++;
+    w |= (uint32_t)(*p++) << 8;
+    w |= (uint32_t)(*p++) << 16;
+    w |= (uint32_t)(*p++) << 24;
+    return w;
+#endif
+}
+
+static BLAKE2_INLINE uint64_t load64(const void *src) {
+#if defined(NATIVE_LITTLE_ENDIAN)
+    uint64_t w;
+    memcpy(&w, src, sizeof w);
+    return w;
+#else
+    const uint8_t *p = (const uint8_t *)src;
+    uint64_t w = *p++;
+    w |= (uint64_t)(*p++) << 8;
+    w |= (uint64_t)(*p++) << 16;
+    w |= (uint64_t)(*p++) << 24;
+    w |= (uint64_t)(*p++) << 32;
+    w |= (uint64_t)(*p++) << 40;
+    w |= (uint64_t)(*p++) << 48;
+    w |= (uint64_t)(*p++) << 56;
+    return w;
+#endif
+}
+
+static BLAKE2_INLINE void store32(void *dst, uint32_t w) {
+#if defined(NATIVE_LITTLE_ENDIAN)
+    memcpy(dst, &w, sizeof w);
+#else
+    uint8_t *p = (uint8_t *)dst;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+#endif
+}
+
+static BLAKE2_INLINE void store64(void *dst, uint64_t w) {
+#if defined(NATIVE_LITTLE_ENDIAN)
+    memcpy(dst, &w, sizeof w);
+#else
+    uint8_t *p = (uint8_t *)dst;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+#endif
+}
+
+static BLAKE2_INLINE uint64_t load48(const void *src) {
+    const uint8_t *p = (const uint8_t *)src;
+    uint64_t w = *p++;
+    w |= (uint64_t)(*p++) << 8;
+    w |= (uint64_t)(*p++) << 16;
+    w |= (uint64_t)(*p++) << 24;
+    w |= (uint64_t)(*p++) << 32;
+    w |= (uint64_t)(*p++) << 40;
+    return w;
+}
+
+static BLAKE2_INLINE void store48(void *dst, uint64_t w) {
+    uint8_t *p = (uint8_t *)dst;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+    w >>= 8;
+    *p++ = (uint8_t)w;
+}
+
+static BLAKE2_INLINE uint32_t rotr32(const uint32_t w, const unsigned c) {
+    return (w >> c) | (w << (32 - c));
+}
+
+static BLAKE2_INLINE uint64_t rotr64(const uint64_t w, const unsigned c) {
+    return (w >> c) | (w << (64 - c));
+}
+
+void clear_internal_memory(void *v, size_t n);
+
+#endif