Remove svn:executable from a documentation file.

Should fix the buildbot failure caused by it.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342502 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/SupportLibrary.rst b/docs/SupportLibrary.rst
old mode 100755
new mode 100644