Don't detect indentation when in Makefile2/Automake syntax

[mattdangerw]

Same as the default Make syntax shipped with sublime does. Otherwise you can get in a weird state where you have some spaces in a Makefile, so sublime detects you want spaces instead of tabs, and suddenly its impossible to type a proper tab into you makefile

You never want to translate tabs to spaces in make, so we shouldn't try to detect spacing

[mattdangerw]

I was pretty much just copying what is shipped in the default sublime package https://github.com/malkomalko/default_sublime3_packages/blob/master/Makefile/Makefile.sublime-settings

[ptomato]

Thanks!