### Please describe the problem.

Adding BUILDER=stack support in 441573a9 breaks building debian based packages.

### What steps will reproduce the problem?

[[!format sh """
$ debian/rules clean
dh clean
   dh_testdir
   dh_auto_clean
        make -j1 clean
make[1]: Entering directory '/home/jtgeibel/repos/launchpad.net/git-annex'
debian/cabal-wrapper clean
debian/cabal-wrapper: 14: debian/cabal-wrapper: cabal: not found
Makefile:101: recipe for target 'clean' failed
make[1]: *** [clean] Error 127
make[1]: Leaving directory '/home/jtgeibel/repos/launchpad.net/git-annex'
dh_auto_clean: make -j1 clean returned exit code 2
debian/rules:12: recipe for target 'clean' failed
make: *** [clean] Error 2
"""]]

### What version of git-annex are you using? On what operating system?

6.20160114 (Ubuntu wily & trusty)

### Please provide any additional information below.

I've patched this locally as follows.  In the Makefile I've assumed that both cabal and stack support a clean command.

[[!format patch """
diff --git a/Makefile b/Makefile                                                                                                                              
index 342152c..977855a 100644                                                                                                                                               
--- a/Makefile                                                                                                                                                              
+++ b/Makefile                                                                                                                                                              
@@ -98,7 +98,7 @@ docs: mans                                                                                                                                                                 
                --exclude='users/*' --exclude='devblog/*' --exclude='thanks'                                                                                                                 
                                                                                                                                                                                             
 clean:                                                                                                                                                                                      
-       $(BUILDER) clean                                                                                                                                                                     
+       if [ "$(BUILDER)" != ./Setup ]; then $(BUILDER) clean; fi                                                                                                                            
        rm -rf tmp dist git-annex $(mans) configure  *.tix .hpc \                                                                                                                            
                doc/.ikiwiki html dist tags Build/SysConfig.hs \                                                                                                                             
                Setup Build/InstallDesktopFile Build/EvilSplicer \                                                                                                                                                
diff --git a/debian/rules b/debian/rules
index e6ee592..3345fee 100755
--- a/debian/rules
+++ b/debian/rules
@@ -1,6 +1,6 @@
 #!/usr/bin/make -f
 
-export BUILDER=debian/cabal-wrapper
+export BUILDER=./Setup
 
 STANDALONE_BUILD=$(shell grep -qe '^Package: git-annex-standalone' debian/control \
                          && echo 1 || echo 0)
"""]]


### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)

git-annex has been a great way for me to explore both Haskell and software packaging.

I enjoyed the interview on LWN.

> I don't think this is a bug, I think build dependencies were not
> installed when building the package. [[done]] --[[Joey]]
