python-utils-r1.eclass: Do not prefer Jython & PyPy over CPython

Fix _PYTHON_ALL_IMPLS to list Jython & PyPy before CPython versions,
therefore causing them not to be implicitly preferred over CPython.

The implementation reordering done in b284e54 ("reorder implementations
in semi-ascending order") has caused PyPy & Jython to be listed after
CPython. While seemingly it was more intuitive to list third-party
implementations after the reference one, it also implicitly caused them
to be preferred by python-exec.

eclass/python-utils-r1.eclass

@@ -41,10 +41,10 @@ inherit toolchain-funcs
 # @DESCRIPTION:
 # All supported Python implementations, most preferred last.
 _PYTHON_ALL_IMPLS=(
+	jython2_7
+	pypy pypy3
 	python2_7
 	python3_3 python3_4 python3_5
-	pypy pypy3
-	jython2_7
 )
 readonly _PYTHON_ALL_IMPLS