erlang: pass erl_xcomp_sysroot to configure

This is required for building the 'crypto', 'odbc', 'ssh'
and 'ssl' Erlang applications. These apps are skipped
regardless of whether they're enabled and their dependencies
can be met if this environment variable isn't set.

Signed-off-by: Frank Hunleth <fhunleth@troodon-software.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/erlang/erlang.mk

@@ -17,6 +17,10 @@ ERLANG_INSTALL_STAGING = YES
 # The configure checks for these functions fail incorrectly
 ERLANG_CONF_ENV = ac_cv_func_isnan=yes ac_cv_func_isinf=yes
 
+# Set erl_xcomp variables. See xcomp/erl-xcomp.conf.template
+# for documentation.
+ERLANG_CONF_ENV += erl_xcomp_sysroot=$(STAGING_DIR)
+
 ERLANG_CONF_OPT = --without-javac
 HOST_ERLANG_CONF_OPT = --without-javac