remove libfuzzerInitializeCounters and fix counter incrementing code

Author: kyakdan

src/cmd/compile/internal/typecheck/builtin.go

@@ -266,9 +266,6 @@ func libfuzzerTraceConstCmp2(uint16, uint16)
 func libfuzzerTraceConstCmp4(uint32, uint32)
 func libfuzzerTraceConstCmp8(uint64, uint64)
 
-// This function should be called by the fuzz target on start to register the 8bit counters with libfuzzer
-func libfuzzerInitializeCounters()
-
 // architecture variants
 var x86HasPOPCNT bool
 var x86HasSSE41 bool

src/cmd/compile/internal/typecheck/builtin/runtime.go

@@ -464,8 +464,8 @@ func (o *orderState) edge() {
 	// Saturated Counters, however, decreases the overall performance.
 	o.append(ir.NewIfStmt(base.Pos,
 		ir.NewBinaryExpr(base.Pos, ir.OEQ, counter, ir.NewInt(0xff)),
-		[]ir.Node{ir.NewAssignOpStmt(base.Pos, ir.OADD, counter, ir.NewInt(1))},
-		[]ir.Node{ir.NewAssignStmt(base.Pos, counter, ir.NewInt(1))}))
+		[]ir.Node{ir.NewAssignStmt(base.Pos, counter, ir.NewInt(1))},
+		[]ir.Node{ir.NewAssignOpStmt(base.Pos, ir.OADD, counter, ir.NewInt(1))}))
 }
 
 // orderBlock orders the block of statements in n into a new slice,