Merging r155844:

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r155844 | spop | 2012-04-30 13:06:58 -0700 (Mon, 30 Apr 2012) | 8 lines

fix typo

Thanks to "Gabor Greif" <ggreif@gmail.com> for reporting this problem.

The configure flag should be --with-default-sysroot as documented, and
not --with-sysroot.  The reason we don't want to define --with-sysroot
is that GCC has a configure flag by that name and it has a different
semantics.
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llvm-svn: 155852