Allow any test to be executed via a %run command.

Configure %run with COMPILER_RT_EMULATOR:

  $ cmake -DCOMPILER_RT_EMULATOR="qemu-arm -L $SYSROOT"

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@207707 91177308-0d34-0410-b5e6-96231b3b80d8
Add %run to all lit tests

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@207709 91177308-0d34-0410-b5e6-96231b3b80d8