[ELF] - Fix for PR28976 - Corrupted section contents when using linker scripts

This is fix for PR28976.

Problem was that in scanRelocs, we computed relocation offset too early 
for case when linkerscript was used. Patch fixes the issue 
delaying the calculation.

Differential revision: https://reviews.llvm.org/D23655

llvm-svn: 279264
diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp
index dca84e1..0f03857 100644
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -566,7 +566,7 @@
         continue;
       Offset = PieceI->OutputOff + RI.r_offset - PieceI->InputOff;
     } else {
-      Offset = C.getOffset(RI.r_offset);
+      Offset = RI.r_offset;
     }
 
     // This relocation does not require got entry, but it is relative to got and