r600: Clear visited structure before running.

Fixes random crashes in for-loop piglit.

Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
Reviewed-by: Matt Arsenault <Matthew.Arsenault@amd.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232181 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed