libnspr: fix 64-bit build

On some architectures (found on x86_64, but probably others too),
libnspr builds with -m32 unless it is configured for 64-bit build.  So
force 64-bit build on 64-bit architectures.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/libnspr/libnspr.mk

@@ -12,6 +12,8 @@ LIBNSPR_INSTALL_STAGING = YES
 LIBNSPR_CONF_ENV = HOST_CFLAGS="-g -O2" \
 		   HOST_LDFLAGS="-lc"
 # NSPR mixes up --build and --host
-LIBNSPR_CONF_OPT = --host=$(GNU_HOST_NAME)
+LIBNSPR_CONF_OPT  = --host=$(GNU_HOST_NAME)
+LIBNSPR_CONF_OPT += --$(if $(BR2_ARCH_IS_64),en,dis)able-64bit
+LIBNSPR_CONF_OPT += --$(if $(BR2_INET_IPV6),en,dis)able-ipv6
 
 $(eval $(autotools-package))