Add capnproto (#473)

* Add capnproto

* update capnproto

* build capnproto for mingw

* capnproto: disable shared build under Windows

packages/c/capnproto/xmake.lua

@@ -0,0 +1,27 @@
+package("capnproto")
+
+    set_homepage("https://github.com/capnproto/capnproto")
+    set_description("Cap'n Proto serialization/RPC system - core tools and C++ library.")
+
+    set_urls("https://github.com/capnproto/capnproto/archive/v$(version).zip")
+    add_versions("0.8.0", "9a5e090b1f3ad39bb47fed5fd03672169493674ce273418b76c868393fced2e4")
+    add_versions("0.7.0", "1054a879e174b8f797f1b506fedb14ecba5556c656e33ac51bd0a62bd90f925f")
+
+    if is_plat("windows") then
+        add_configs("shared", {description = "Build shared library.", default = false, type = "boolean", readonly = true})
+    end
+
+    add_deps("cmake", "zlib")
+
+    on_install("windows", "mingw", "linux", "macosx", "bsd", function (package)
+        local configs = {}
+        table.insert(configs, "-DBUILD_TESTING=OFF")
+        table.insert(configs, "-DCMAKE_BUILD_TYPE=" .. (package:debug() and "Debug" or "Release"))
+        table.insert(configs, "-DBUILD_SHARED_LIBS=" .. (package:config("shared") and "ON" or "OFF"))
+        import("package.tools.cmake").install(package, configs)
+        package:addenv("PATH", "bin")
+    end)
+
+    on_test(function (package)
+        assert(package:has_cxxtypes("capnp::MallocMessageBuilder", {configs = {languages = "c++14"}, includes = "capnp/message.h"}))
+    end)