s/mxio_get_startup_handle/mx_get_startup_handle/

For MG-228: "get startup handles should not live in mxio"

Change-Id: I23eb64cb095275279ced44d4f81cdc1db6ba9a21
diff --git a/src/syscall/mx/mxruntime/mxruntime_cgo.go b/src/syscall/mx/mxruntime/mxruntime_cgo.go
index 7005b53..ac1b9f5 100644
--- a/src/syscall/mx/mxruntime/mxruntime_cgo.go
+++ b/src/syscall/mx/mxruntime/mxruntime_cgo.go
@@ -8,12 +8,11 @@
 
 import "syscall/mx"
 
-// #cgo fuchsia LDFLAGS: -lmxio
-// #include "mxio/util.h"
+// #include "magenta/process.h"
 import "C"
 
 func getStartupHandle(info HandleInfo) mx.Handle {
 	id := uint32(info.Arg)<<16 | uint32(info.Type)
-	h := C.mxio_get_startup_handle(C.uint32_t(id))
+	h := C.mx_get_startup_handle(C.uint32_t(id))
 	return mx.Handle(h)
 }