MC: Add support for mach-o build_version

LC_BUILD_VERSION is a new load command superseding the previously used
LC_XXX_MIN_VERSION commands. This adds an assembler directive along with
encoding/streaming support.

llvm-svn: 320661
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
index 9a23e61..01d1659 100644
--- a/llvm/lib/MC/MCAssembler.cpp
+++ b/llvm/lib/MC/MCAssembler.cpp
@@ -88,7 +88,7 @@
     : Context(Context), Backend(Backend), Emitter(Emitter), Writer(Writer),
       BundleAlignSize(0), RelaxAll(false), SubsectionsViaSymbols(false),
       IncrementalLinkerCompatible(false), ELFHeaderEFlags(0) {
-  VersionMinInfo.Major = 0; // Major version == 0 for "none specified"
+  VersionInfo.Major = 0; // Major version == 0 for "none specified"
 }
 
 MCAssembler::~MCAssembler() = default;
@@ -107,7 +107,7 @@
   IncrementalLinkerCompatible = false;
   ELFHeaderEFlags = 0;
   LOHContainer.reset();
-  VersionMinInfo.Major = 0;
+  VersionInfo.Major = 0;
 
   // reset objects owned by us
   getBackend().reset();