Makefile: Use order-only deps for directories

[glebm]

See https://www.gnu.org/software/make/manual/html_node/Prerequisite-Types.html

With this PR the targets only depend on directories' existence, but not on their timestamps.

Fixes #2727, fixes #1992, fixes #1433.

[glebm]

@sgbeal I think this might also solve the problem described in #2727. Does it?

[sgbeal]

@glebm if i knew how to use git/github properly, and could figure out how to pull this for a local test, i could probably tell you that :/. (i'm a Fossil SCM guy, not a git guy :/) i have no personal experience with order-only prerequisites, so i can't say with certainty whether it resolves the problem.

[glebm]

@sgbeal Like this:

git clone https://github.com/glebm/libsass.git && cd libsass && git checkout patch-2

[sgbeal]

@glebm

 [stephan@host:~/cvs/libsass]$ git checkout patch-2
 error: pathspec 'patch-2' did not match any file(s) known to git.

That's after doing a fresh clone.

[glebm]

OK, try git checkout origin/patch-2 or git checkout origin patch-2

[mgreter]

Finally someone found the real solution 👍 if I only knew about order-only deps, was looking for this up and down the documentation for make 😃 also tested it quickly on my windows machine and seems to work.

[mgreter]

P.s. git clone https://github.com/glebm/libsass.git --branch patch-2

[sgbeal]

@glebm Unfortunately:

$ git checkout origin/patch-2
error: pathspec 'origin/patch-2' did not match any file(s) known to git.
$ git checkout origin patch-2
error: pathspec 'patch-2' did not match any file(s) known to git.

@mgreter that does the trick.

This is exactly why i'm not a git guy - even the most banal operations are cryptic :/.

So, after building...

[stephan@host:~/cvs/libsass]$ m install PREFIX=$HOME
'lib/libsass.a' -> '/home/stephan/lib/libsass.a'

(noting that ~/lib existed beforehand)

Success!

[xzyfer]

Thank you all for seeing this through ❤️