Report detected scops using the new diagnostics

We now report the following:

$ polly-clang -O3 -mllvm -polly -mllvm -polly-report test.c  -c \
  -gline-tables-only

note: Polly detected an optimizable loop region (scop) in function 'foo'
test.c:2: Start of scop
test.c:3: End of scop
note: Polly detected an optimizable loop region (scop) in function 'bar'
test.c:9: Start of scop
test.c:13: End of scop