package/python-pycryptodomex: fix package build with gcc 4.8

python-pycryptodomex uses C99 features like variable
declaration in for-loop statement, while old compilers
assumes C89 by default.

This patch explicitly specifies C99 standard.

Signed-off-by: Oleg Lyovin <ovlevin@salutedevices.com>
[yann.morin.1998@free.fr: use TARGET/HOST_CFLAGS]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/python-pycryptodomex/python-pycryptodomex.mk

@@ -13,5 +13,8 @@ PYTHON_PYCRYPTODOMEX_LICENSE = \
 	Public Domain (pycrypto original code)
 PYTHON_PYCRYPTODOMEX_LICENSE_FILES = LICENSE.rst Doc/LEGAL/COPYRIGHT.pycrypto
 
+PYTHON_PYCRYPTODOMEX_ENV = CFLAGS="$(TARGET_CFLAGS) -std=c99"
+HOST_PYTHON_PYCRYPTODOMEX_ENV = CFLAGS="$(HOST_CFLAGS) -std=c99"
+
 $(eval $(python-package))
 $(eval $(host-python-package))