[dev.regabi] cmd/compile: clean up debug flag (-d) handling [generated]

The debug table is not as haphazard as flags, but there are still
a few mismatches between command-line names and variable names.
This CL moves them all into a consistent home (var Debug, like var Flag).

Code updated automatically using the rf command below.
A followup CL will make a few manual cleanups, leaving this CL
completely automated and easier to regenerate during merge
conflicts.

[git-generate]
cd src/cmd/compile/internal/gc
rf '
	add main.go var Debug struct{}
	mv Debug_append Debug.Append
	mv Debug_checkptr Debug.Checkptr
	mv Debug_closure Debug.Closure
	mv Debug_compilelater Debug.CompileLater
	mv disable_checknil Debug.DisableNil
	mv debug_dclstack Debug.DclStack
	mv Debug_gcprog Debug.GCProg
	mv Debug_libfuzzer Debug.Libfuzzer
	mv Debug_checknil Debug.Nil
	mv Debug_panic Debug.Panic
	mv Debug_slice Debug.Slice
	mv Debug_typeassert Debug.TypeAssert
	mv Debug_wb Debug.WB
	mv Debug_export Debug.Export
	mv Debug_pctab Debug.PCTab
	mv Debug_locationlist Debug.LocationLists
	mv Debug_typecheckinl Debug.TypecheckInl
	mv Debug_gendwarfinl Debug.DwarfInl
	mv Debug_softfloat Debug.SoftFloat
	mv Debug_defer Debug.Defer
	mv Debug_dumpptrs Debug.DumpPtrs

	mv flag.go:/parse.-d/-1,/unknown.debug/+2 parseDebug

	mv debugtab Debug parseDebug \
		debugHelpHeader debugHelpFooter \
		debug.go

	# Remove //go:generate line copied from main.go
	rm debug.go:/go:generate/-+
'

Change-Id: I625761ca5659be4052f7161a83baa00df75cca91
Reviewed-on: https://go-review.googlesource.com/c/go/+/272246
Trust: Russ Cox <rsc@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/gc/pgen.go

@@ -291,7 +291,7 @@ func compilenow(fn *Node) bool {
 	if fn.IsMethod() && isInlinableButNotInlined(fn) {
 		return false
 	}
-	return Flag.LowerC == 1 && Debug_compilelater == 0
+	return Flag.LowerC == 1 && Debug.CompileLater == 0
 }
 
 // isInlinableButNotInlined returns true if 'fn' was marked as an