[llvm-objcopy][MachO] Implement --only-section

Reviewers: alexshap, rupprecht, jdoerfert, jhenderson

Reviewed By: alexshap, rupprecht, jhenderson

Subscribers: mgorny, jakehehrlich, abrachet, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65541
diff --git a/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp b/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
index b48a0d8..ed2b3eb 100644
--- a/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
+++ b/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
@@ -35,6 +35,7 @@
           .str();
   S.Segname =
       StringRef(Sec.segname, strnlen(Sec.segname, sizeof(Sec.sectname))).str();
+  S.CanonicalName = (Twine(S.Segname) + "," + S.Sectname).str();
   S.Addr = Sec.addr;
   S.Size = Sec.size;
   S.Offset = Sec.offset;