package/libxcrypt: disable obsolete API

Disable obsolete API following upstream feedback as it raises build
failures on some architectures such as nds32le or arc and because this
API is unsecure: https://github.com/besser82/libxcrypt/issues/122

Fixes:
 - http://autobuild.buildroot.org/results/5ae235b6ec66ac86efadaa2847307be58064c167

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/libxcrypt/libxcrypt.mk

@@ -14,4 +14,7 @@ LIBXCRYPT_AUTORECONF = YES
 # Some warnings turn into errors with some sensitive compilers
 LIBXCRYPT_CONF_OPTS = --disable-werror
 
+# Disable obsolete and unsecure API
+LIBXCRYPT_CONF_OPTS += --disable-obsolete_api
+
 $(eval $(autotools-package))