#2 build from tar.gz with svn installed

[Gaetan Lehmann]

clcc fails to build from tar.gz with svn installed on the system with the error:

CMake Error at /usr/local/Cellar/cmake/3.1.1_1/share/cmake/Modules/FindSubversion.cmake:110 (message):
Command "/usr/bin/svn info /tmp/clcc-PP9u2p" failed with output:

svn: E155007: '/tmp/clcc-PP9u2p' is not a working copy

Call Stack (most recent call first):
CMakeLists.txt:25 (Subversion_WC_INFO)

this is easily fixed with the attached patch