wolfssl: install into staging

wolfssl is a library, so it should be installed into staging so other
packages can find the header files / library.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/wolfssl/wolfssl.mk

@@ -7,6 +7,7 @@
 WOLFSSL_VERSION = 3.14.0
 WOLFSSL_SITE = https://github.com/wolfSSL/wolfssl/archive
 WOLFSSL_SOURCE = v$(WOLFSSL_VERSION)-stable.tar.gz
+WOLFSSL_INSTALL_STAGING = YES
 
 WOLFSSL_LICENSE = GPL-2.0
 WOLFSSL_LICENSE_FILES = COPYING LICENSING