cmd/*: remove negative uint checks

All of these are uints of different sizes, so checking >= 0 or < 0 are
effectively no-ops.

Found with staticcheck.

Change-Id: I16ac900eb7007bc8f9018b302136d42e483a4180
Reviewed-on: https://go-review.googlesource.com/56950Reviewed-by: Matt Layher <mdlayher@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Matt Layher <mdlayher@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -227,13 +227,13 @@ func (o Op) format(s fmt.State, verb rune, mode fmtMode) {
 
 func (o Op) oconv(s fmt.State, flag FmtFlag, mode fmtMode) {
 	if flag&FmtSharp != 0 || mode != FDbg {
-		if o >= 0 && int(o) < len(goopnames) && goopnames[o] != "" {
+		if int(o) < len(goopnames) && goopnames[o] != "" {
 			fmt.Fprint(s, goopnames[o])
 			return
 		}
 	}
 
-	if o >= 0 && int(o) < len(opnames) && opnames[o] != "" {
+	if int(o) < len(opnames) && opnames[o] != "" {
 		fmt.Fprint(s, opnames[o])
 		return
 	}

src/cmd/internal/obj/sym.go

@@ -34,7 +34,6 @@ package obj
 import (
 	"cmd/internal/objabi"
 	"fmt"
-	"log"
 	"math"
 )
 
@@ -46,9 +45,6 @@ func Linknew(arch *LinkArch) *Link {
 	ctxt.Pathname = objabi.WorkingDir()
 
 	ctxt.Headtype.Set(objabi.GOOS)
-	if ctxt.Headtype < 0 {
-		log.Fatalf("unknown goos %s", objabi.GOOS)
-	}
 
 	ctxt.Flag_optimize = true
 	ctxt.Framepointer_enabled = objabi.Framepointer_enabled(objabi.GOOS, arch.Name)

src/cmd/trace/trace.go

@@ -449,9 +449,6 @@ func generateTrace(params *traceParams) (ViewerData, error) {
 		if setGStateErr != nil {
 			return ctx.data, setGStateErr
 		}
-		if ctx.gstates[gRunnable] < 0 || ctx.gstates[gRunning] < 0 || ctx.threadStats.insyscall < 0 {
-			return ctx.data, fmt.Errorf("invalid state after processing %v: runnable=%d running=%d insyscall=%d", ev, ctx.gstates[gRunnable], ctx.gstates[gRunning], ctx.threadStats.insyscall)
-		}
 
 		// Ignore events that are from uninteresting goroutines
 		// or outside of the interesting timeframe.