David Wales 2e8a71bf31 Update build-osx.md: Add mkdir
mkdir line added in line 97 to prevent the following error:

    -bash: /Users/dwales/.twister/twister.conf: No such file or directory
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..
2014-05-05 17:05:41 +10:00
2014-01-08 18:05:02 +03:00