nginx: fix install paths

This patch fixes Nginx install paths. I tried to build the native variant
for testing purpose and had errors.

- Use path variable instead of /usr
- Replace the absolute path symlink with a relative one

Signed-off-by: Gaylord CHARLES <gaylord.charles@veo-labs.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-webserver/recipes-httpd/nginx/nginx.inc

@@ -93,9 +93,9 @@ do_install () {
             >> ${D}${sysconfdir}/tmpfiles.d/${BPN}.conf
     fi
     install -d ${D}${sysconfdir}/${BPN}
-    ln -snf ${localstatedir}/run/${BPN} ${D}${sysconfdir}/${BPN}/run
+    lnr ${D}${localstatedir}/run/${BPN} ${D}${sysconfdir}/${BPN}/run
     install -d ${D}${NGINX_WWWDIR}
-    mv ${D}/usr/html ${D}${NGINX_WWWDIR}/
+    mv ${D}${exec_prefix}/html ${D}${NGINX_WWWDIR}/
     chown ${NGINX_USER}:www-data -R ${D}${NGINX_WWWDIR}
 
     install -d ${D}${sysconfdir}/init.d