[projects/test-suite] Fix RUNSAFELY make variable definition.

 To allow the RUNUNDER script to be run with parameters, the
 the definition of RUNSAFELY needs to quote the interpolation
 of RUNUNDER.

Patch by Doug Gilmore


git-svn-id: https://llvm.org/svn/llvm-project/test-suite/trunk@192485 91177308-0d34-0410-b5e6-96231b3b80d8