delete build-aux directory as all its files are generated by autogen.sh

doc/Makefile.am

@@ -59,7 +59,7 @@ uninstall-local:
 #	vector_scal_c.texi vector_scal_cuda.texi vector_scal_opencl.texi vector_scal_opencl_codelet.texi
 
 # Rule to update documentation on web server. Should only be used locally.
-PUBLISHHOST	= sync
+PUBLISHHOST	?= sync
 update-web: starpu.html
 	sed -i 's/gcc\.html#Attribute-Syntax/http:\/\/gcc.gnu.org\/onlinedocs\/gcc\/Attribute-Syntax.html#Attribute-Syntax/' starpu.html
 	scp starpu.pdf starpu.html $(PUBLISHHOST):/web/runtime/html/StarPU