remove old forklock stub and replace it with sync.RWMutex

Signed-off-by: leongross <leon.gross@9elements.com>

src/syscall/forklock.go

@@ -1,31 +1,12 @@
-//go:build tinygo && linux && !wasip1 && !wasip2 && !darwin && !baremetal
+//go:build tinygo && linux && !wasip1 && !wasip2 && !darwin && !baremetal && !tinygo.wasm
 
 package syscall
 
-// This is the original ForkLock:
-//
-// var ForkLock sync.RWMutex
-//
-// This requires importing sync, but importing sync causes an import loop:
-//
-// package tinygo.org/x/drivers/examples/net/tcpclient
-//        imports bytes
-//        imports io
-//        imports sync
-//        imports internal/task
-//        imports runtime/interrupt
-//        imports device/arm
-//        imports syscall
-//        imports sync: import cycle not allowed
-//
-// So for now, make our own stubbed-out ForkLock that doesn't use sync..
+import (
+	"sync"
+)
 
-type forklock struct{}
-
-func (f forklock) RLock()   {}
-func (f forklock) RUnlock() {}
-
-var ForkLock forklock
+var ForkLock sync.RWMutex
 
 func CloseOnExec(fd int) {
 	system.CloseOnExec(fd)
@@ -34,5 +15,3 @@ func CloseOnExec(fd int) {
 func SetNonblock(fd int, nonblocking bool) (err error) {
 	return system.SetNonblock(fd, nonblocking)
 }
-
-// type SysProcAttr struct{}