cmake: properly find older msgpack versions

Change-Id: I63e4cd903395d99092e0c0de47efaf7799793d05

CMakeLists.txt

@@ -15,15 +15,11 @@ set (includedir "${CMAKE_INSTALL_FULL_INCLUDEDIR}")
 set (VERSION ${CMAKE_PROJECT_VERSION})
 
 find_package (PkgConfig REQUIRED)
-find_package(msgpackc-cxx QUIET CONFIG)
+find_package(msgpackc-cxx QUIET CONFIG NAMES msgpackc-cxx msgpack)
 if(msgpackc-cxx_FOUND)
   add_library(msgpack-cxx ALIAS msgpackc-cxx)
 else()
-  find_package(msgpack-cxx CONFIG)
-  if(NOT msgpack-cxx_FOUND)
-    find_package(msgpack CONFIG REQUIRED)
-    add_library(msgpack-cxx ALIAS msgpack)
-  endif()
+  find_package(msgpack-cxx CONFIG REQUIRED)
 endif()
 
 find_package(fmt)