[ELF] Fix typo in comment for getISDThunkSec [NFC]
[ELF] Fix typo in comment for getISDThunkSec [NFC]

The ISR in the comment should read ISD for InputSectionDescription. The use
of ISR (InputSectionRange) was from the original implementation that did not
use the sections from InputSectionDescription directly.



git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@317469 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld