wendelin.core: v↑ 2.0.alpha2.pre1 -> 2.0.alpha2.post1

Finishing touches to release wendelin.core 2.0.alpha2:

- Switch to using File IO provided by Pygolang
- Fix build_dso on clean checkout (not relevant for SlapOS)

nexedi/wendelin.core@11e023cf...ad6305c0

Tested via:

ERP5: https://nexedijs.erp5.net/#/test_result_module/20220127-586CEAFD
Wendelin: https://nexedijs.erp5.net/#/test_result_module/20220127-8444F82A

component/wendelin.core/buildout.cfg

@@ -50,7 +50,7 @@ CGO_LDFLAGS += -Wl,-rpath=${zlib:location}/lib
 recipe  = slapos.recipe.build:gitclone
 repository = https://lab.nexedi.com/nexedi/wendelin.core.git
 branch   = master
-revision = wendelin.core-2.0.alpha1-20-g11e023cf
+revision = wendelin.core-2.0.alpha2-1-gad6305c0
 # dir is pretty name as top-level recipe
 location = ${buildout:parts-directory}/wendelin.core
 git-executable = ${git:location}/bin/git