fix in-place assignments of arbitrary objects to variables with inferred Python builtin/extension types

--HG--
extra : amend_source : b920a1b9cf4249bb95a7f1a310222080c26dc326

always use UtilityCode.load_cached() for reading dependencies of helpers as it's highly likely that they will be reused by others as well

generate cdef classes and closure classes in a deterministic order to reduce C code churn on regeneration
also fixes a problem where duplicate entries (one used, one unused) could be selected somewhat arbitrarily during type sorting (apparently applied to but worked for memoryview/-slice)

--HG--
extra : amend_source : 47d569b1b6faffc3f1f24da25b2a0c98cbb0bd15

TST: Fix detection of Windows platform

The (k=k) can results in "multiple unsequenced modifications to 'kind'"
warning when this macro is expanded twice in the same expression.