build: Disable libusb and libmnl for embedded builds

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Change-Id: Ie7900098ffda7cebfab81c08b25b0001e6fd98ec
diff --git a/configure.ac b/configure.ac
index 990d0e7..bf85c07 100644
--- a/configure.ac
+++ b/configure.ac
@@ -381,7 +381,9 @@
 	AM_CONDITIONAL(ENABLE_UTILITIES, false)
 	AM_CONDITIONAL(ENABLE_GB, false)
 	AM_CONDITIONAL(ENABLE_GNUTLS, false)
+	AM_CONDITIONAL(ENABLE_LIBMNL, false)
 	AM_CONDITIONAL(ENABLE_LIBSCTP, false)
+	AM_CONDITIONAL(ENABLE_LIBUSB, false)
 	AM_CONDITIONAL(ENABLE_PCSC, false)
 	AM_CONDITIONAL(ENABLE_PSEUDOTALLOC, true)
 	AM_CONDITIONAL(ENABLE_SERCOM_STUB, true)