Adding cython v0.20.2 in third-party.

third_party/cython/src/Tools/site_scons/site_tools/cython.py

+"""
+Tool to run Cython files (.pyx) into .c and .cpp.
+
+TODO:
+ - Add support for dynamically selecting in-process Cython
+   through CYTHONINPROCESS variable.
+ - Have a CYTHONCPP option which turns on C++ in flags and
+   changes output extension at the same time
+
+VARIABLES:
+ - CYTHON - The path to the "cython" command line tool.
+ - CYTHONFLAGS - Flags to pass to the "cython" command line tool.
+
+AUTHORS:
+ - David Cournapeau
+ - Dag Sverre Seljebotn
+
+"""
+import SCons
+from SCons.Builder import Builder
+from SCons.Action import Action
+
+#def cython_action(target, source, env):
+#    print target, source, env
+#    from Cython.Compiler.Main import compile as cython_compile
+#    res = cython_compile(str(source[0]))
+
+cythonAction = Action("$CYTHONCOM")
+
+def create_builder(env):
+    try:
+        cython = env['BUILDERS']['Cython']
+    except KeyError:
+        cython = SCons.Builder.Builder(
+                  action = cythonAction,
+                  emitter = {},
+                  suffix = cython_suffix_emitter,
+                  single_source = 1)
+        env['BUILDERS']['Cython'] = cython
+
+    return cython
+
+def cython_suffix_emitter(env, source):
+    return "$CYTHONCFILESUFFIX"
+
+def generate(env):
+    env["CYTHON"] = "cython"
+    env["CYTHONCOM"] = "$CYTHON $CYTHONFLAGS -o $TARGET $SOURCE"
+    env["CYTHONCFILESUFFIX"] = ".c"
+
+    c_file, cxx_file = SCons.Tool.createCFileBuilders(env)
+
+    c_file.suffix['.pyx'] = cython_suffix_emitter
+    c_file.add_action('.pyx', cythonAction)
+
+    c_file.suffix['.py'] = cython_suffix_emitter
+    c_file.add_action('.py', cythonAction)
+
+    create_builder(env)
+
+def exists(env):
+    try:
+#        import Cython
+        return True
+    except ImportError:
+        return False