gifdec: add package (#2712)

packages/g/gifdec/xmake.lua

@@ -0,0 +1,24 @@
+package("gifdec")
+    set_homepage("https://github.com/lecram/gifdec")
+    set_description("small C GIF decoder")
+
+    add_urls("https://github.com/lecram/gifdec.git")
+    add_versions("2021.12.04", "1dcbae19363597314f6623010cc80abad4e47f7c")
+
+    on_install(function (package)
+        io.writefile("xmake.lua", [[
+            add_rules("mode.release", "mode.debug")
+            target("gifdec")
+                set_kind("$(kind)")
+                add_files("gifdec.c")
+                add_headerfiles("gifdec.h)")
+                if is_plat("windows") and is_kind("shared") then
+                    add_rules("utils.symbols.export_all", {export_classes = true})
+                end
+        ]])
+        import("package.tools.xmake").install(package)
+    end)
+
+    on_test(function (package)
+        assert(package:has_cfuncs("gd_open_gif", {includes = "gifdec.h"}))
+    end)