Switch to Brew's OpenSSL headers/libraries on OS X

Apple deprecated OpenSSL and stopped providing its headers on newer versions of OS X. These
changes adjust CMake build files so that they look for Brew's OpenSSL instead (or a custom
one if provided by the user).
For other systems, it uses CMake's own search to find headers/libraries.
Signed-off-by: Otavio Rodolfo Piske <opiske@redhat.com>

src/CMakeLists.txt

@@ -72,19 +72,22 @@ INSTALL(FILES MQTTAsync.h MQTTClient.h MQTTClientPersistence.h
 IF (PAHO_WITH_SSL)
 SET(OPENSSL_LIB_SEARCH_PATH "" CACHE PATH "Directory containing OpenSSL libraries")
     SET(OPENSSL_INC_SEARCH_PATH "" CACHE PATH "Directory containing OpenSSL includes")
-    SET(OPENSSL_LIBRARIES ssl crypto)
 
-    find_path(OPENSSL_INCLUDE_DIR openssl/ssl.h
-	HINTS ${OPENSSL_INC_SEARCH_PATH}/include)
-    find_library(OPENSSL_LIB NAMES ssl libssl
-	HINTS ${OPENSSL_DIR}/lib ${OPENSSL_DIR}/lib64)
-    find_library(OPENSSLCRYPTO_LIB NAMES ssl libssl
-	HINTS ${OPENSSL_DIR}/lib ${OPENSSL_DIR}/lib64)
+    IF (${CMAKE_SYSTEM_NAME} STREQUAL "Darwin")
+      SET(OPENSSL_BREW_PATH "/usr/local/opt/openssl")
+    ENDIF (${CMAKE_SYSTEM_NAME} STREQUAL "Darwin")
 
-    message(STATUS "OpenSSL hint ${PENSSL_INC_SEARCH_PATH} (includes) / ")
-    message(STATUS "OpenSSL headers found at ${OPENSSL_INCLUDE_DIR}")
-    message(STATUS "OpenSSL library found at ${OPENSSL_LIB}")
-    message(STATUS "OpenSSL Crypto library found at ${OPENSSLCRYPTO_LIB}")
+    FIND_PATH(OPENSSL_INCLUDE_DIR openssl/ssl.h
+        HINTS ${OPENSSL_INC_SEARCH_PATH}/include ${OPENSSL_BREW_PATH}/include/)
+    FIND_LIBRARY(OPENSSL_LIB NAMES ssl libssl
+        HINTS ${OPENSSL_BREW_PATH}/lib ${OPENSSL_DIR}/lib ${OPENSSL_DIR}/lib64)
+    FIND_LIBRARY(OPENSSLCRYPTO_LIB NAMES ssl libssl
+      	HINTS ${OPENSSL_BREW_PATH}/lib ${OPENSSL_DIR}/lib ${OPENSSL_DIR}/lib64)
+
+    MESSAGE(STATUS "OpenSSL hint ${PENSSL_INC_SEARCH_PATH} (includes) / ")
+    MESSAGE(STATUS "OpenSSL headers found at ${OPENSSL_INCLUDE_DIR}")
+    MESSAGE(STATUS "OpenSSL library found at ${OPENSSL_LIB}")
+    MESSAGE(STATUS "OpenSSL Crypto library found at ${OPENSSLCRYPTO_LIB}")
 
     INCLUDE_DIRECTORIES(
         ${OPENSSL_INCLUDE_DIR}
@@ -105,4 +108,3 @@ SET(OPENSSL_LIB_SEARCH_PATH "" CACHE PATH "Directory containing OpenSSL librarie
         RUNTIME DESTINATION bin
         LIBRARY DESTINATION lib)
 ENDIF()
-