bug#55846: make bootstrap -j2 fails on macOS

[Mattias Engdegård]

I have no idea what the intention was, but it's slightly confusing that the 
originating commit (de3d0b572d) was ostensibly made to cope with make 
parallelism. (CC:ing the author, Jan Djärv, in case he still remembers 
anything.)

Just making one target depend on the other, as in the diff below, makes it 
work, but I'm not sure of the purpose of ns_check_file.

--- a/nextstep/Makefile.in
+++ b/nextstep/Makefile.in
@@ -47,7 +47,9 @@ .PHONY:
 
 all: ${ns_appdir} ${ns_appbindir}/Emacs ${ns_applibexecdir}/Emacs.pdmp
 
-${ns_check_file} ${ns_appdir}: ${srcdir}/${ns_appsrc} ${ns_appsrc}
+${ns_check_file}: ${ns_appdir}
+
+${ns_appdir}: ${srcdir}/${ns_appsrc} ${ns_appsrc}
        rm -rf ${ns_appdir}
        ${MKDIR_P} ${ns_appdir}
        ( cd ${srcdir}/${ns_appsrc} ; tar cfh - . ) | \