Testsuite: Add 'torture-init-done', and use it to conditionalize implicit 'torture...

Testsuite: Add 'torture-init-done', and use it to conditionalize implicit 'torture-init'

Recent commit d6654a4be3ba44c0d57be7c8a51d76d9721345e1
"Let each 'lto_init' determine the default 'LTO_OPTIONS', and 'torture-init' the 'LTO_TORTURE_OPTIONS'"
made 'torture-init' non-idempotent re 'LTO_TORTURE_OPTIONS', in order to catch
certain classes of errors.  Now, most of all '*.exp' files have 'torture-init'
followed by 'set-torture-options' before 'gcc-dg-runtest' etc., and therefore
don't run into the latter's
"Some callers set torture options themselves; don't override those." code.
Some '*.exp' files however do 'torture-init' but not 'set-torture-options', and
therefore we can't any longer conditionalize the implicit 'torture-init' by
'![torture-options-exist]'.

	gcc/testsuite/
	* lib/torture-options.exp (torture-init-done): Add.
	* lib/gcc-dg.exp (gcc-dg-runtest): Use it to conditionalize
	implicit 'torture-init'.
	* lib/gfortran-dg.exp (gfortran-dg-runtest): Likewise.
	* lib/obj-c++-dg.exp (obj-c++-dg-runtest): Likewise.
	* lib/objc-dg.exp (objc-dg-runtest): Likewise.