[ELF2] target specific section order

[Easwaran, Shankar via llvm-commits]

Hi,

Architectures like Hexagon needs specific placements of sections as 
required by the ABI. Examples of such sections are small data, and 
section .start that need to be at the very beginning ?

Can I add a function to override  the Default Section order to the one 
that the target can override with ?

Shankar Easwaran