Makefile indentation

[Geert Janssens]

Hi,

Thanks to Christian's fine work our c sources and header files are now 
consistently indented.

I am about to make a number of changes in several Makefile.am files and notice 
the indentation is a mess. Sometimes tabs are used, sometimes spaces, or even 
combinations of both.

What is the preferred way to indent Makefiles ? If there is some consensus I 
can fix the ones I am about to change anyway (obviously in a separate commit).

Since we've chosen for space indentation in the c files, perhaps it's best to 
continue this practise for the makefiles, like 4 spaces per indentation level.

Any comments ?

Geert