package/python-cryptography: add missing openssl build dependency

Commit
01764876e3d4e7ab95c8365f1c83e6c12d49757c ("package/python-cryptography:
bump version to 36.0.1") incorrectly removed the build dependency on
openssl. This causes the following build failure:

build/temp.linux-x86_64-3.10/_openssl.c:575:10: fatal error: openssl/opensslv.h: No such file or directory
  575 | #include <openssl/opensslv.h>
      |          ^~~~~~~~~~~~~~~~~~~~

as OpenSSL is no longer guaranteed to be built before
python-cryptography (the Config.in file still had a "select
BR2_PACKAGE_OPENSSL" guaranteeing that OpenSSL would be built, but not
necessarily before).

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/python-cryptography/python-cryptography.mk

@@ -12,7 +12,11 @@ PYTHON_CRYPTOGRAPHY_LICENSE = Apache-2.0 or BSD-3-Clause
 PYTHON_CRYPTOGRAPHY_LICENSE_FILES = LICENSE LICENSE.APACHE LICENSE.BSD
 PYTHON_CRYPTOGRAPHY_CPE_ID_VENDOR = cryptography_project
 PYTHON_CRYPTOGRAPHY_CPE_ID_PRODUCT = cryptography
-PYTHON_CRYPTOGRAPHY_DEPENDENCIES = host-python-setuptools-rust host-python-cffi host-rustc
+PYTHON_CRYPTOGRAPHY_DEPENDENCIES = \
+	host-python-setuptools-rust \
+	host-python-cffi \
+	host-rustc \
+	openssl
 PYTHON_CRYPTOGRAPHY_ENV = \
 	$(PKG_CARGO_ENV) \
 	PYO3_CROSS_LIB_DIR="$(STAGING_DIR)/usr/lib/python$(PYTHON3_VERSION_MAJOR)"