cmd/5g etc: merge simple case expressions onto fewer lines

The c2go translation left a lot of case expressions on separate lines.
Merge expressions onto single lines subject to these constraints:

* Max 4 clauses, all literals or names
* Don't move expressions with comments

The change was created by running http://play.golang.org/p/yHajs72h-g:

$ mergecase cmd/internal/{ld,gc,obj}/*.go cmd/internal/obj/*/*.go

Passes toolstash -cmp.

Change-Id: Iba41b390d302e5486e5dc6ba7599a92270676556
Reviewed-on: https://go-review.googlesource.com/7593
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
diff --git a/src/cmd/internal/gc/gsubr.go b/src/cmd/internal/gc/gsubr.go
index 4a9f895..357bca1 100644
--- a/src/cmd/internal/gc/gsubr.go
+++ b/src/cmd/internal/gc/gsubr.go
@@ -250,9 +250,7 @@
 func Isfat(t *Type) bool {
 	if t != nil {
 		switch t.Etype {
-		case TSTRUCT,
-			TARRAY,
-			TSTRING,
+		case TSTRUCT, TARRAY, TSTRING,
 			TINTER: // maybe remove later
 			return true
 		}
@@ -384,8 +382,7 @@
 		case PAUTO:
 			a.Name = obj.NAME_AUTO
 
-		case PPARAM,
-			PPARAMOUT:
+		case PPARAM, PPARAMOUT:
 			a.Name = obj.NAME_PARAM
 
 		case PFUNC:
@@ -409,8 +406,7 @@
 			a.Type = obj.TYPE_FCONST
 			a.Val = mpgetflt(n.Val.U.Fval)
 
-		case CTINT,
-			CTRUNE:
+		case CTINT, CTRUNE:
 			a.Sym = nil
 			a.Type = obj.TYPE_CONST
 			a.Offset = Mpgetfix(n.Val.U.Xval)