curl: use the system certificates

Signed-off-by: Cristian Morales Vega <cristian@samknows.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@42661 3c298f89-4303-0410-b956-a3cf2f4a3e73
curl: only set ca path for openssl

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@42662 3c298f89-4303-0410-b956-a3cf2f4a3e73