Add instructions for building with MSAN

site/user/special/msan.md

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+Running with Memory Sanitizer

[scroggo, 2016/04/20 14:39:10]

I'm not very familiar with markdown, so the format is pretty basic. I'm open to
suggestions.

The instructions are also pretty basic. They are borrowed from
crrev.com/1665823002.

[hal.canary, 2016/04/20 14:45:43]

The msan build builds Clang from scratch, so you need to download Clang first:

Add the following to your gclient file:

    target_os = ['llvm']

Then run:

    gclient sync

Build
-----

    out/Debug/dm -v --match ~Codec ~BlurLargeImage ~FontMgrAndroidParser
Run
---

    out/Debug/dm -v --match ~Codec ~BlurLargeImage ~FontMgrAndroidParser

[scroggo, 2016/04/20 15:02:19]

It looks like you're recommending
- four spaces before commands
- no "$"
- no "./"
?

Done. FWIW, our other docs don't seem to be consistent about using a "$".

+=============================
+
+Prerequisites
+-------------
+
+The msan build builds Clang from scratch, so you need to download Clang first:
+
+Add the following to your gclient file:
+target_os = ['llvm']
+
+Then run:
+$ gclient sync

[hal.canary, 2016/04/20 14:48:11]

Run it this way instead:

    bin/sync-and-gyp --deps=llvm

[scroggo, 2016/04/20 15:02:19]

Done.

+
+Build
+-----
+
+$ ./tools/xsan_build memory dm
+
+Run
+---
+
+$ out/Debug/dm -v --match ~Codec ~BlurLargeImage ~FontMgrAndroidParser