When detecting OpenSSL, look for 1.0.1, and in homebrew location

Previously we would detect the system openssl on OSX, and then fail
to use it, since we required Open 1.0.1 or later.  That's silly!

Instead of looking for RAND_add(), look for TLSv1_1_method(): it was
introduced in 1.0.1, and is also present in LibreSSL.

Also, add the hombebrew path to our search path here.

Fixes bug 23602; bugfix on 0.2.7.2-alpha.

changes/ticket23602

@@ -0,0 +1,6 @@
+  o Minor bugfixes (build):
+    - When searching for OpenSSL, don't accept any OpenSSL library that lacks
+      TLSv1_1_method(): Tor doesn't build with those versions.  Additionally,
+      look in /usr/local/opt/openssl, if it's present.  These changes
+      together repair the default build on OSX systems with Homebrew
+      installed. Fixes bug 23602; bugfix on 0.2.7.2-alpha.

configure.ac

@@ -612,11 +612,12 @@ AC_ARG_WITH(ssl-dir,
       fi
   ])
 
+AC_MSG_NOTICE([Now, we'll look for OpenSSL >= 1.0.1])
 TOR_SEARCH_LIBRARY(openssl, $tryssldir, [-lssl -lcrypto $TOR_LIB_GDI],
-    [#include <openssl/rand.h>],
-    [void RAND_add(const void *buf, int num, double entropy);],
-    [RAND_add((void*)0,0,0);], [],
-    [/usr/local/openssl /usr/lib/openssl /usr/local/ssl /usr/lib/ssl /usr/local /usr/athena /opt/openssl])
+    [#include <openssl/ssl.h>],
+    [struct ssl_method_st; const struct ssl_method_st *TLSv1_1_method(void);],
+    [TLSv1_1_method();], [],
+    [/usr/local/opt/openssl /usr/local/openssl /usr/lib/openssl /usr/local/ssl /usr/lib/ssl /usr/local /usr/athena /opt/openssl])
 
 dnl XXXX check for OPENSSL_VERSION_NUMBER == SSLeay()