Use local SHA512 header

Actually use the local private SHA512 header instead of relying on the
OpenSSL one for no good reason. Add definition for expected macro
SHA512_DIGEST_LENGTH.

src/getentropy_aix.c

@@ -39,7 +39,7 @@
 #include <string.h>
 #include <termios.h>
 
-#include <openssl/sha.h>
+#include "hash/sha512.h"
 
 #include <libperfstat.h>
 

src/getentropy_hpux.c

@@ -41,7 +41,8 @@
 #include <errno.h>
 #include <unistd.h>
 #include <time.h>
-#include <openssl/sha.h>
+
+#include "hash/sha512.h"
 
 #include <sys/vfs.h>
 

src/getentropy_linux.c

@@ -47,7 +47,8 @@
 #include <errno.h>
 #include <unistd.h>
 #include <time.h>
-#include <openssl/sha.h>
+
+#include "hash/sha512.h"
 
 #include <linux/types.h>
 #include <linux/random.h>

src/hash/sha512.h

@@ -31,6 +31,8 @@
 
 #include <sys/types.h>
 
+#define SHA512_DIGEST_LENGTH		64
+
 typedef struct SHA512Context {
 	uint64_t state[8];
 	uint64_t count[2];