libosmocore: Use PACKAGECONFIG to enable gnutls and libsctp support

Change-Id: Iff9dd88e23a3cdcf333f9c365381b56afd2285c3
diff --git a/recipes-osmocom/libosmocore/libosmocore.inc b/recipes-osmocom/libosmocore/libosmocore.inc
index e5b34ae..40a42bc 100644
--- a/recipes-osmocom/libosmocore/libosmocore.inc
+++ b/recipes-osmocom/libosmocore/libosmocore.inc
@@ -6,11 +6,15 @@
 
 LIC_FILES_CHKSUM = "file://COPYING;md5=751419260aa954499f7abaabaa882bbe"
 
-DEPENDS = "libtalloc gnutls lksctp-tools"
+DEPENDS = "libtalloc"
 
 PACKAGECONFIG ??= "\
+    gnutls \
     libusb \
+    libsctp \
     "
+PACKAGECONFIG[gnutls] = "--enable-gnutls,--disable-gnutls,gnutls,"
 PACKAGECONFIG[libusb] = "--enable-libusb,--disable-libusb,libusb,"
+PACKAGECONFIG[libsctp] = "--enable-libsctp,--disable-libsctp,lksctp-tools,"
 
 inherit autotools pkgconfig