heimdal: disable parallel make

It still seems to suffer from issues. Fixes:
http://autobuild.buildroot.net/results/e21/e2176cb5adacdad14371d4828f13a1c23f0e18d5/

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/heimdal/heimdal.mk

@@ -8,6 +8,7 @@ HEIMDAL_VERSION = 7.1.0
 HEIMDAL_SITE = http://www.h5l.org/dist/src
 HOST_HEIMDAL_DEPENDENCIES = host-e2fsprogs host-ncurses host-pkgconf
 HEIMDAL_INSTALL_STAGING = YES
+HEIMDAL_MAKE = $(MAKE1)
 # static because of -fPIC issues with e2fsprogs on x86_64 host
 HOST_HEIMDAL_CONF_OPTS = \
 	--disable-shared \