sip: remove in favour of meta-oe recipe

Version 4.12 of python-pyqt that we are about to upgrade to requires sip 4.19 which is already in meta-oe, so this version is no longer working. We shouldn't really be carrying a duplicate recipe here, but on the other hand we don't want to be adding a hard dependency on meta-oe either. As a compromise, drop the sip recipe here and require the user to add meta-oe in order to build it, and a corresponding note to the README.

---
 README                                   |  7 +++++
 recipes-qt4/recipes-python/sip_4.16.4.bb | 54 --------------------------------
 2 files changed, 7 insertions(+), 54 deletions(-)
 delete mode 100644 recipes-qt4/recipes-python/sip_4.16.4.bb

index 49c3ab2..cebdacd 100644
@@ -23,6 +23,13 @@ subdirectory: meta
 branch: master
 revision: HEAD
 
+If you want to build python-pyqt you will also need meta-oe:
+
+URI: git://github.com/openembedded/meta-openembedded
+subdirectory: meta-oe
+branch: master
+revision: HEAD
+
 
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