OSX: fix OpenSSL detection for 10.11. Fixes cpp-netlib#690

Author: anonimal

CMakeLists.txt

@@ -49,7 +49,15 @@ set(Boost_USE_MULTI_THREADED ON)
 find_package(Boost 1.58.0 REQUIRED COMPONENTS system thread)
 
 if (CPP-NETLIB_ENABLE_HTTPS)
-    find_package( OpenSSL )
+  if (APPLE)
+    # If we're on OS X check for Homebrew's copy of OpenSSL instead of Apple's
+    if (NOT OpenSSL_DIR)
+      execute_process (COMMAND brew --prefix openssl
+        OUTPUT_VARIABLE OPENSSL_ROOT_DIR
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+    endif()
+  endif()
+  find_package(OpenSSL)
 endif()
 
 find_package( Threads )