[patch] Simplify arange output

[Rafael Espíndola]

I was looking at emitDebugARanges and noticed it was the only user of
 SectionMap.

The attached patch changes it to compute SectionMap and saves a call to
sort.

Cheers,
Rafael
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20150128/b6fe8524/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: t.patch
Type: application/octet-stream
Size: 7735 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20150128/b6fe8524/attachment.obj>