add g2o (#1611)

* Update xmake.lua

* Update xmake.lua

* Update xmake.lua

* Update xmake.lua

* add g2o

* Update xmake.lua

packages/g/g2o/xmake.lua

@@ -0,0 +1,32 @@
+package("g2o")
+    set_homepage("http://openslam.org/g2o.html")
+    set_description("g2o: A General Framework for Graph Optimization")
+
+    add_urls("https://github.com/RainerKuemmerle/g2o/archive/refs/tags/$(version).tar.gz", {version = function (version)
+        return version:gsub("%.", "") .. "_git"
+    end})
+    add_urls("https://github.com/RainerKuemmerle/g2o.git")
+    add_versions("2020.12.23", "20af80edf8fd237e29bd21859b8fc734e615680e8838824e8b3f120c5f4c1672")
+
+    add_deps("cmake", "eigen")
+
+    on_install("linux", "windows", "macosx", function (package)
+        local configs = {"-DG2O_BUILD_APPS=OFF", "-DG2O_BUILD_EXAMPLES=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)
+    end)
+
+    on_test(function (package)
+        assert(package:check_cxxsnippets({test = [[
+            #include "g2o/core/factory.h"
+            #include "g2o/core/optimization_algorithm_factory.h"
+            #include "g2o/core/sparse_optimizer.h"
+            #include "g2o/stuff/command_args.h"
+
+            void test() {
+                g2o::SparseOptimizer optimizer;
+                optimizer.setVerbose(false);
+            }
+        ]]}, {configs = {languages = "c++14"}}))
+    end)