Open up libzfs_run_process/libzfs_load_module

Recently helper functions were added to libzfs_util to load a kernel
module or execute a process.  Initially this functionality was limited
to libzfs but it has become clear there will be other consumers.  This
change opens up the interface so it may be used where appropriate.

lib/libzfs/libzfs_util.c

@@ -631,7 +631,7 @@ libzfs_module_loaded(const char *module)
 	return result;
 }
 
-static int
+int
 libzfs_run_process(const char *path, char *argv[])
 {
 	pid_t pid;
@@ -657,13 +657,14 @@ libzfs_run_process(const char *path, char *argv[])
 	return -1;
 }
 
-static int
+int
 libzfs_load_module(const char *module)
 {
 	char *argv[4] = {"/sbin/modprobe", "-q", (char *)module, (char *)0};
 
 	if (libzfs_module_loaded(module))
 		return 0;
+
 	return libzfs_run_process("/sbin/modprobe", argv);
 }