gas: sframe: command line option takes precedence

over gas directive to emit .sframe section.

Fix PR gas/33175 sframe: --gsframe=no does not disable when
.cfi_sections directive with .sframe

--gsframe=no should also disable generation of SFrame section when
explicit CFI directive:
  .cfi_sections .sframe
is specified in the input.  This means we need to track whether SFrame
generation was explicitly disabled by the user.  Introduce a new enum to
facilitate disambiguation between GEN_SFRAME_DEFAULT_NONE and
GEN_SFRAME_DISABLED.

While fixing the bug by adding the enum, keep the upcoming requirement
in mind: we will also need to disambiguate between
--enable-default-sframe and user-specified --gsframe/--gsframe=yes.  The
intent is to not display SFrame related warnings or errors like:

  as_bad (_(".sframe not supported for target"));

for unsupported targets if --enable-default-sframe is in effect.

This implies we need to have a four state enum (
GEN_SFRAME_DEFAULT_NONE, GEN_SFRAME_CONFIG_ENABLED,
GEN_SFRAME_DISABLED, GEN_SFRAME_ENABLED)

gas/
	PR gas/33175
	* dw2gencfi.c (cfi_finish): Check state of flag_gen_sframe to
	determine whether any SFrame section is generated.
	* as.h (enum gen_sframe_option): New definition.
	* as.c (parse_args): Keep track of whether the flag is
	explicitly enabled or disabled

gas/testsuite/
	PR gas/33175
	* gas/cfi-sframe/cfi-sframe-common-1.d: Remove redundant
	--gsframe.
	* gas/cfi-sframe/cfi-sframe.exp:  Add new test.
	* gas/cfi-sframe/cfi-sframe-common-1c.d: New test.  No SFrame
	section if explicit --gsframe=no.
	* gas/cfi-sframe/cfi-sframe-common-1c.s: New test.