Node.js: fixed global install in some cases.

By default "npm install" switches to non-privileged user to run package scripts
if it is invoked by root.  As a result it may prevent node-gyp from writing to
package directory and break installation of the module.

To disable this switching the --unsafe-perm flag is added.

auto/modules/nodejs

@@ -161,7 +161,7 @@ install: ${NXT_NODE}-$NXT_NODE_INSTALL
 ${NXT_NODE}-install: ${NXT_NODE_TARBALL} \
     $NXT_BUILD_DIR/$NXT_LIB_UNIT_STATIC
 	${NXT_NODE_EXPORTS} && \\
-	${NXT_NPM} install -g ${PWD}/${NXT_NODE_TARBALL}
+	${NXT_NPM} install -g --unsafe-perm ${PWD}/${NXT_NODE_TARBALL}
 
 ${NXT_NODE}-uninstall:
 	${NXT_NPM} uninstall -g unit-http