cmd/v: reimplement -path flag

vlib/os/os_nix.c.v

@@ -8,6 +8,7 @@ import strings
 
 pub const (
 	path_separator = '/'
+	path_delimiter = ':'
 )
 
 const (

vlib/os/os_windows.c.v

@@ -7,6 +7,7 @@ import strings
 
 pub const (
 	path_separator = '\\'
+	path_delimiter = ';'
 )
 
 // Ref - https://docs.microsoft.com/en-us/windows/desktop/winprog/windows-data-types