python3: do not use the system OpenSSL in the host variant

host-python3 currently detect if there is an usable OpenSSL installation
and conditionnaly compiles the 'ssl', '_ssl' and '_hashlib' modules.
This may break compilation if the system's OpenSSL has been updated to
1.1.0 because of a bug in python, see https://bugs.python.org/issue26470
for details.

Unlike Python 2.7, Python 3 unconditionnaly compiles fallbacks for
common hash algorithm, so disabling OpenSSL will still leave Python 3
with implementations of common hash algorithm.

This adds a patch to configure.ac patch to implement a --disable-openssl
option.

Signed-off-by: Nicolas Cavallari <nicolas.cavallari@green-communications.fr>
Tested-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/python3/0031-Add-an-option-to-disable-openssl.patch

@@ -0,0 +1,23 @@
+From: Nicolas Cavallari <nicolas.cavallari@green-communications.fr>
+Subject: [PATCH] Add an option to disable openssl support.
+
+Signed-off-by: Nicolas Cavallari <nicolas.cavallari@green-communications.fr>
+---
+ configure.ac | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+--- a/configure.ac
++++ b/configure.ac
+@@ -3027,6 +3027,12 @@
+     	     DISABLED_EXTENSIONS="${DISABLED_EXTENSIONS} unicodedata"
+   	  fi])
+ 
++AC_ARG_ENABLE(openssl,
++	AS_HELP_STRING([--disable-openssl], [disable openssl support]),
++	[ if test "$enableval" = "no"; then
++	     DISABLED_EXTENSIONS="${DISABLED_EXTENSIONS} ssl _ssl _hashlib"
++	  fi])
++
+ AC_SUBST(TK)
+ AC_ARG_ENABLE(tk,
+ 	AS_HELP_STRING([--disable-tk], [disable tk]),

package/python3/python3.mk

@@ -36,7 +36,8 @@ HOST_PYTHON3_CONF_OPTS += 	\
 	--enable-unicodedata	\
 	--disable-test-modules	\
 	--disable-idle3		\
-	--disable-ossaudiodev
+	--disable-ossaudiodev	\
+	--disable-openssl
 
 # Make sure that LD_LIBRARY_PATH overrides -rpath.
 # This is needed because libpython may be installed at the same time that