lang/python{27,32,33,34}: Mark MAKE_JOBS_UNSAFE

Parser/pgen code intermittently and non-deterministically fails
at build time causing errors including, among others:

• Parser/pgen.o: file not recognized: File truncated
• pgenmain.c:(.text+0x244): undefined reference to `_Py_pgen'

This is apparently due to incorrect uses of recursive make [1] which
was fixed in the upstream Python 'default' (3.5) branch [2].

This change marks all Python port versions as MAKE_JOBS_UNSANFE until
the the original changeset [1] and the resulting regression in
cross-builds [3], whos fix is still pending, can be backported.

[1] https://bugs.python.org/issue22359
[2] https://hg.python.org/cpython/rev/c2a53aa27cad
[3] https://bugs.python.org/issue22625

PR: 200622
Reported by: marino
MFH: 2015Q3