Fix hiredis detection by cmake (#1620)

See #1618 for details

This fix allows proper hiredis detection on macOS when building with
cmake

src/apps/relay/CMakeLists.txt

@@ -87,17 +87,17 @@ if(WIN32)
 else()
 	find_package(mongo)
 	if(mongo_FOUND)
-    list(APPEND turnserver_LIBS mongo)
-    list(APPEND SOURCE_FILES dbdrivers/dbd_mongo.c)
+        list(APPEND turnserver_LIBS mongo)
+        list(APPEND SOURCE_FILES dbdrivers/dbd_mongo.c)
 		list(APPEND HEADER_FILES dbdrivers/dbd_mongo.h)
 	else()
-    list(APPEND turnserver_DEFINED TURN_NO_MONGO)
+        list(APPEND turnserver_DEFINED TURN_NO_MONGO)
 	endif()
 endif()
 
-find_package(hiredis)
-if(hiredis_FOUND)
-    list(APPEND turnserver_LIBS hiredis::hiredis)
+pkg_check_modules(HIREDIS IMPORTED_TARGET hiredis)
+if(HIREDIS_FOUND)
+    list(APPEND turnserver_LIBS PkgConfig::HIREDIS)
     list(APPEND SOURCE_FILES hiredis_libevent2.c dbdrivers/dbd_redis.c)
     list(APPEND HEADER_FILES hiredis_libevent2.h dbdrivers/dbd_redis.h)
 else()