libstrophe: install into target

Since a7134ce6745 (libstrophe: bump version), the package does in fact build
and install a shared library, so ensure it also ends up in target so it can
be found at runtime.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libstrophe/libstrophe.mk

@@ -10,11 +10,7 @@ LIBSTROPHE_DEPENDENCIES = openssl host-pkgconf
 LIBSTROPHE_AUTORECONF = YES
 LIBSTROPHE_LICENSE = MIT or GPLv3
 LIBSTROPHE_LICENSE_FILES = MIT-LICENSE.txt GPL-LICENSE.txt
-
-# This package does not build a dynamic library, so there is nothing
-# to be installed to the target.
 LIBSTROPHE_INSTALL_STAGING = YES
-LIBSTROPHE_INSTALL_TARGET = NO
 
 ifeq ($(BR2_PACKAGE_EXPAT),y)
 # Passing --without-libxml2 doesn't work, due to how AC_ARG_WITH is