Add loki-mq as submodule

.gitmodules

@@ -27,3 +27,6 @@
 	path = external/libuv
 	url = https://github.com/libuv/libuv
 	branch = v1.x
+[submodule "external/loki-mq"]
+	path = external/loki-mq
+	url = https://github.com/loki-project/loki-mq

CMakeLists.txt

@@ -272,9 +272,12 @@ if(SUBMODULE_CHECK)
     if (NOT WIN32) # we grab libuv for windows separately in win32-setup/libuv. see note in cmake/win32.cmake.
       check_submodule(external/libuv)
     endif()
+    check_submodule(external/loki-mq)
   endif()
 endif()
 
+add_subdirectory(external/loki-mq EXCLUDE_FROM_ALL)
+
 # We only actually need pybind11 with WITH_HIVE, but if we don't load it here then something further
 # down loads a broken PythonInterp that loads Python2, but Python2 headers are not C++17 compatible.
 # So load this here universally so that pybind's more intelligent python finder finds python3.x

external/loki-mq

@@ -0,0 +1 @@
+Subproject commit 719a9b0b58b7520931b83aa3c5ce110172e4c279