Use UD1 instead of UD2

The definition of BTC and friends conflicted with UD1, so fix that.
Without this, our UD1 instruction got printed out as BTC.

Update x86-arch to look for ud1 instead of ud2.
10 jobs for issue-97-define-ud2-inst in 22 minutes and 41 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Install
passed #12686
linux
linux:install

00:00:47

passed #12687
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osx:install

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  Build
passed #12688
linux
linux:build

00:04:23

passed #12689
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osx:build

00:08:45

 
  Test
passed #12690
linux
linux:test

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passed #12691
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osx:test

00:00:51

 
  Ansi Test
passed #12692
linux
linux:ansi-test

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passed #12693
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osx:ansi-test

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  Benchmark
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linux:benchmark

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passed #12695
osx
osx:benchmark

00:04:05