Initialize SubArch in class Triple

[krytarowski]

Summary

LLDB built with asan on NetBSD detected issues in the following code:

void ArchSpec::Clear() {
  m_triple = llvm::Triple();
  m_core = kCore_invalid;
  m_byte_order = eByteOrderInvalid;
  m_distribution_id.Clear();
  m_flags = 0;
}

• lldb/source/Core/ArchSpec.cpp

Runtime error messages:

/public/pkgsrc-tmp/wip/lldb-netbsd/work/.buildlink/include/llvm/ADT/Triple.h:44:7: runtime error: load of value 32639, which is not a valid value for type 'SubArchType'
/public/pkgsrc-tmp/wip/lldb-netbsd/work/.buildlink/include/llvm/ADT/Triple.h:44:7: runtime error: load of value 3200171710, which is not a valid value for type 'SubArchType'
/public/pkgsrc-tmp/wip/lldb-netbsd/work/.buildlink/include/llvm/ADT/Triple.h:44:7: runtime error: load of value 3200171710, which is not a valid value for type 'SubArchType'

Correct this issue with initialization of SubArch() in the class Triple constructor.

Sponsored by <The NetBSD Foundation>

[krytarowski]

Ping?

include/llvm/ADT/Triple.h

private:
   ObjectFormatType ObjectFormat;
 
 public:
   /// @name Constructors
   /// @{
 
   /// Default constructor is the same as an empty string and leaves all
   /// triple fields unknown.
-  Triple() : Data(), Arch(), Vendor(), OS(), Environment(), ObjectFormat() {}
+  Triple()
+      : Data(), Arch(), SubArch(), Vendor(), OS(), Environment(),
+        ObjectFormat() {}
 
   explicit Triple(const Twine &Str);
   Triple(const Twine &ArchStr, const Twine &VendorStr, const Twine &OSStr);
   Triple(const Twine &ArchStr, const Twine &VendorStr, const Twine &OSStr,
          const Twine &EnvironmentStr);
 
   bool operator==(const Triple &Other) const {
     return Arch == Other.Arch && SubArch == Other.SubArch &&