python-cryptography: fix build by disabling setup requirements

python-cryptography tries to install other packages during setup.

However, this isn't needed, since they should have been already
resolved/installed via LEDE/OpenWrt's build system dep logic.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

lang/python-cryptography/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=cryptography
 PKG_VERSION:=1.5.1
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://pypi.python.org/packages/21/e1/37fc14f9d77924e84ba0dcb88eb8352db914583af229287c6c965d66ba0d

lang/python-cryptography/patches/001-disable-setup-requirements.patch

@@ -0,0 +1,12 @@
+diff --git a/setup.py b/setup.py
+index b5c05df..a777dd7 100644
+--- a/setup.py
++++ b/setup.py
+@@ -266,6 +266,7 @@ class DummyPyTest(test):
+ with open(os.path.join(base_dir, "README.rst")) as f:
+     long_description = f.read()
+ 
++setup_requirements=[]
+ 
+ setup(
+     name=about["__title__"],