package/freeradius-server: fix libkrb5 build

Fix the following libkrb5 build failure raised since the addition of the
package in commit 736c4c1655d93652a9a7e79235bbe726b3d46176:

configure: error: in `/home/giuliobenetti/autobuild/run/instance-2/output-1/build/freeradius-server-3.2.0/src/modules/rlm_krb5':
configure: error: cannot run test program while cross compiling

Fixes:
 - http://autobuild.buildroot.org/results/3968d611458060480d341bd60f7c50209a0ace15

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Acked-by: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/freeradius-server/freeradius-server.mk

@@ -15,6 +15,12 @@ FREERADIUS_SERVER_CPE_ID_PRODUCT = freeradius
 FREERADIUS_SERVER_DEPENDENCIES = libtalloc
 FREERADIUS_SERVER_AUTORECONF = YES
 
+# We're patching src/modules/rlm_krb5/configure.ac
+define FREERADIUS_SERVER_RUN_KRB5_AUTOCONF
+	cd $(@D)/src/modules/rlm_krb5; $(AUTOCONF) -I$(@D)
+endef
+FREERADIUS_SERVER_PRE_CONFIGURE_HOOKS += FREERADIUS_SERVER_RUN_KRB5_AUTOCONF
+
 # some compiler checks are not supported while cross compiling.
 # instead of removing those checks, we cache the answers
 FREERADIUS_SERVER_CONF_OPTS += \