testsuite, fortran: adapt tests for ifort's 'start' behavior

testsuite, fortran: adapt tests for ifort's 'start' behavior

The modified tests array-slices-bad.exp and vla-type.exp both set a
breakpoint at the first real statement in the respective executables.

Normally, the expected behavior of fortran_runto_main for these would be
the stopping of the debugger at exactly the first statment in the code.

Strangely, neither gfortran nor ifx seem to do this for these tests.
Instead, issuing 'start' in ifx (for either of the 2 tests) lets GDB
stop at the 'program ...' line and gfortran stops at a variable
declaration line.  E.g. for vla-type it stops at

  41        type(five)               :: fivearr (2)

So, actually, ifort's behavior can be considered to be a bit more
'correct' here.  This patch remove the fortran_runto_main in the
two tests and instead uses runto to directly run to the first breakpoint
set at the first program statement.  This works with both compiler
behaviors and makes the tests more robust.

Approved-by: Kevin Buettner <kevinb@redhat.com>