Add rule python.cython

Add test python/cython/example
Move test pybind to python/pybind

Author: Freed-Wu

tests/projects/python/cython/example/src/example.py

@@ -0,0 +1 @@
+print("Hello, world!")

tests/projects/python/cython/example/xmake.lua

@@ -0,0 +1,7 @@
+add_rules("mode.debug", "mode.release")
+add_requires("python 3.x")
+
+target("example")
+    add_rules("python.cython")
+    add_files("src/*.py")
+    add_packages("python")

tests/projects/pybind/example/src/example.cpp renamed to tests/projects/python/pybind/example/src/example.cpp

@@ -0,0 +1,62 @@
+--!A cross-platform build utility based on Lua
+--
+-- Licensed under the Apache License, Version 2.0 (the "License");
+-- you may not use this file except in compliance with the License.
+-- You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+--
+-- Copyright (C) 2015-present, TBOOX Open Source Group.
+--
+-- @author      Wu, Zhenyu
+-- @file        xmake.lua
+--
+
+rule("python.cython")
+    add_deps("python.library")
+    set_extensions(".py", ".pyx")
+
+    on_load(function (target)
+        local language = target:extraconf("rules", "python.cython", "language")
+        if language == "c" then
+            target:add("deps", "c")
+        elseif language == "c++" then
+            target:add("deps", "c++")
+        end
+    end)
+
+    before_buildcmd_file(function (target, batchcmds, sourcefile, opt)
+        import("lib.detect.find_tool")
+
+        local cython = assert(find_tool("cython"), "cython not found! please `pip install cython`.")
+        local language = target:extraconf("rules", "python.cython", "language")
+        local ext = "c"
+        local arg = "-3"
+        if language == "c++" then
+            ext = "cc"
+            arg = arg .. "+"
+        end
+        local dirname = path.join(target:autogendir(), "rules", "python", "cython")
+        local sourcefile_c = path.join(dirname, path.basename(sourcefile) .. "." .. ext)
+
+        -- add objectfile
+        local objectfile = target:objectfile(sourcefile_c)
+        table.insert(target:objectfiles(), objectfile)
+
+        -- add commands
+        batchcmds:show_progress(opt.progress, "${color.build.object}compiling.python %s", sourcefile)
+        batchcmds:mkdir(path.directory(sourcefile_c))
+        batchcmds:vrunv(cython.program, {arg, "-o", path(sourcefile_c), path(sourcefile)})
+        batchcmds:compile(sourcefile_c, objectfile)
+
+        -- add deps
+        batchcmds:add_depfiles(sourcefile)
+        batchcmds:set_depmtime(os.mtime(objectfile))
+        batchcmds:set_depcache(target:dependfile(objectfile))
+    end)