[PATCH, doc RFA] Add "skip regexp"

[Doug Evans]

Simon Marchi writes:
  > On 16-02-16 08:07 PM, Doug Evans wrote:
  > > +# Test -fi + -fu.
  > > +
  > > +if ![runto_main] {
  > > +    fail "Can't run to main"
  > > +    return
  > > +}
  > > +
  > > +set test "step using -fi + -fu"
  > > +gdb_test_no_output "skip delete"
  > > +gdb_test "skip -fi skip1.c -fu test_skip" \
  > > +    "Function test_skip in file skip1.c will be skipped when  
stepping\."
  > > +gdb_breakpoint "test_skip_file_and_function"
  > > +gdb_breakpoint "end_test_skip_file_and_function"
  > > +gdb_test "call test_skip_file_and_function ()" "silently stop."
  >
  > Hi Doug,
  >
  > I just saw a failure of this test on a target that doesn't have inferior  
calls.  It
  > seems to me like the function call isn't fundamental to the test and it  
could be
  > avoided by organizing things differently.  What do you think?
  >
  > Otherwise, we would need to add a
  >
  >   if [target_info exists gdb,cannot_call_functions] {

Bleah, righto.

Fix forthcoming.
I need to cleanup skip.exp first.