nginx-module-njs: include debug symbols from njs command line tool.

Refs: https://trac.nginx.org/nginx/ticket/1872

debian/Makefile

diff --git a/debian/Makefile b/debian/Makefile
index 38672bc..f1573b1 100644
--- a/debian/Makefile
+++ b/debian/Makefile
@@ -120,7 +120,7 @@
 	mkdir -p $$(INSTALLDIR)/usr/share/doc/nginx-module-njs
 	install -m644 $$(BUILDDIR_nginx)/extra/njs-$(MODULE_VERSION_njs)/CHANGES $$(INSTALLDIR)/usr/share/doc/nginx-module-njs/
 	mkdir -p $$(INSTALLDIR)/usr/bin
-	install -m755 -s $$(CURDIR)/debian/extra/njs-$(MODULE_VERSION_njs)/build/njs $$(INSTALLDIR)/usr/bin/
+	install -m755 $$(CURDIR)/debian/extra/njs-$(MODULE_VERSION_njs)/build/njs $$(INSTALLDIR)/usr/bin/
 endef
 export MODULE_PREINSTALL_njs