Add D++ library.

vendor/DPP/cmake/dpp-config.cmake

@@ -0,0 +1,21 @@
+# dpp-config.cmake - package configuration file
+
+## Get current filesystem path (will a prefixed by where this package was installed)
+get_filename_component(SELF_DIR "${CMAKE_CURRENT_LIST_FILE}" PATH)
+
+## Use this directory to include dpp which has the rest of the project targets
+include(${SELF_DIR}/dpp.cmake)
+
+## Set OpenSSl directory for macos. It is also in our main CMakeLists.txt, but this file is independent from that.
+if(APPLE)
+	if(CMAKE_APPLE_SILICON_PROCESSOR)
+		set(OPENSSL_ROOT_DIR "/opt/homebrew/opt/openssl")
+	else()
+		set(OPENSSL_ROOT_DIR "/usr/local/opt/openssl")
+	endif()
+	find_package(OpenSSL REQUIRED)
+endif()
+
+# Search for libdpp dependencies
+include(CMakeFindDependencyMacro)
+find_dependency(OpenSSL REQUIRED)