python: sitecustomize checks path before remove

This fixes issues when calling python scripts print `'import sitecustomize' failed; use -v for traceback`

Closes #18338.

Signed-off-by: Samuel John <github@SamuelJohn.de>
python: tweak tk patch for python 2.7.4

Closes #19026. Fixes #19020 (half-of)

Signed-off-by: Samuel John <github@SamuelJohn.de>
python: Removed --with-dtrace: patch not compatib.

http://bugs.python.org/issue13405 seems not
to be ready for 2.7.4. Neither merged nor a
patch available. Feel free to submit a pull
request if there is a 2.7.4-compatible
dtrace patch.
MacCPUs: add .avx? helper