Merge OutputSectionBase and OutputSection. NFC.

Now that all special sections are SyntheticSections, we only need one
OutputSection class.

llvm-svn: 296127
diff --git a/lld/ELF/Target.cpp b/lld/ELF/Target.cpp
index 3cace69..046b6a2 100644
--- a/lld/ELF/Target.cpp
+++ b/lld/ELF/Target.cpp
@@ -65,7 +65,7 @@
     if (!IS || !IS->OutSec)
       continue;
 
-    uint8_t *ISLoc = cast<OutputSection<ELFT>>(IS->OutSec)->Loc + IS->OutSecOff;
+    uint8_t *ISLoc = cast<OutputSection>(IS->OutSec)->Loc + IS->OutSecOff;
     if (ISLoc <= Loc && Loc < ISLoc + IS->template getSize<ELFT>())
       return IS->template getLocation<ELFT>(Loc - ISLoc) + ": ";
   }