Don't lose the thumb bit by using relocations with sections.

This fixes a regression from r205076.

llvm-svn: 206047
diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index e802c01..cd92b75 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -813,6 +813,13 @@
   if (Flags & ELF::SHF_TLS)
     return true;
 
+  // If the symbol is a thumb function the final relocation must set the lowest
+  // bit. With a symbol that is done by just having the symbol have that bit
+  // set, so we would lose the bit if we relocated with the section.
+  // FIXME: We could use the section but add the bit to the relocation value.
+  if (SD->getFlags() & ELF_Other_ThumbFunc)
+    return true;
+
   if (TargetObjectWriter->needsRelocateWithSymbol(Type))
     return true;
   return false;