Since Xcode 5.1, the apple tools actually support using the
official, correct syntax for the ext instructions. This syntax
is already used in a number of places already - use it consistently,
and get rid of the compatibility hacks.
Previously the assembly sources had mixed indentation consisting
of both spaces and tabs, making it quite hard to read unless
the right tab size was used in the editor.
Tabs have been interpreted as 4 spaces in most cases, matching
the surrounding code.
