Allow "DHE" and "kDHE" as synonyms of "EDH" and "kEDH" when specifiying ciphers

The standard terminology in https://tools.ietf.org/html/rfc5426 is
"DHE".  "openssl ciphers" outputs "DHE" (for the most part).  But
users of the library currently cannot specify "DHE", they must
currently specify "EDH".

This change allows users to specify the common term in cipher suite
strings without breaking backward compatibility.

ssl/ssl.h

@@ -244,7 +244,8 @@ extern "C" {
 #define SSL_TXT_kDHr		"kDHr" 
 #define SSL_TXT_kDHd		"kDHd"
 #define SSL_TXT_kDH 		"kDH"
-#define SSL_TXT_kEDH		"kEDH"
+#define SSL_TXT_kEDH		"kEDH" /* alias for kDHE */
+#define SSL_TXT_kDHE		"kDHE"
 #define SSL_TXT_kKRB5     	"kKRB5"
 #define SSL_TXT_kECDHr		"kECDHr"
 #define SSL_TXT_kECDHe		"kECDHe"
@@ -268,7 +269,8 @@ extern "C" {
 
 #define	SSL_TXT_DSS		"DSS"
 #define SSL_TXT_DH		"DH"
-#define SSL_TXT_EDH		"EDH" /* same as "kEDH:-ADH" */
+#define SSL_TXT_DHE		"DHE" /* same as "kDHE:-ADH" */
+#define SSL_TXT_EDH		"EDH" /* alias for DHE */
 #define SSL_TXT_ADH		"ADH"
 #define SSL_TXT_RSA		"RSA"
 #define SSL_TXT_ECDH		"ECDH"

ssl/ssl_ciph.c

@@ -242,6 +242,7 @@ static const SSL_CIPHER cipher_aliases[]={
 	{0,SSL_TXT_kDHd,0,    SSL_kDHd,  0,0,0,0,0,0,0,0},
 	{0,SSL_TXT_kDH,0,     SSL_kDHr|SSL_kDHd,0,0,0,0,0,0,0,0},
 	{0,SSL_TXT_kEDH,0,    SSL_kEDH,  0,0,0,0,0,0,0,0},
+	{0,SSL_TXT_kDHE,0,    SSL_kEDH,  0,0,0,0,0,0,0,0},
 	{0,SSL_TXT_DH,0,      SSL_kDHr|SSL_kDHd|SSL_kEDH,0,0,0,0,0,0,0,0},
 
 	{0,SSL_TXT_kKRB5,0,   SSL_kKRB5, 0,0,0,0,0,0,0,0},
@@ -274,6 +275,7 @@ static const SSL_CIPHER cipher_aliases[]={
 
 	/* aliases combining key exchange and server authentication */
 	{0,SSL_TXT_EDH,0,     SSL_kEDH,~SSL_aNULL,0,0,0,0,0,0,0},
+	{0,SSL_TXT_DHE,0,     SSL_kEDH,~SSL_aNULL,0,0,0,0,0,0,0},
 	{0,SSL_TXT_EECDH,0,   SSL_kECDHE,~SSL_aNULL,0,0,0,0,0,0,0},
 	{0,SSL_TXT_ECDHE,0,   SSL_kECDHE,~SSL_aNULL,0,0,0,0,0,0,0},
 	{0,SSL_TXT_NULL,0,    0,0,SSL_eNULL, 0,0,0,0,0,0},