Removed obsolete html.{h, c}.

Gone from upstream in 2.062 as well.
Prefer Port over #if-switching on the compiler.

The issue might have to be revisited (with proper testing)
for FreeBSD or ARM.
Remove LDC-only workaround for 2206.

The bug has been fixed in upstream at least since 2.052.
Remove DMDV2 to align with 2.062 upstream source.
Remove what seems to be an ancient LLVM-only issue 314 fix.
Merge pull request #377 from klickverbot/minimize-dmd-diff

Pick some low-hanging DMD-diff reduction fruit