Automatic header searching

[ParadoxV5]

1. Similar to the library name arg handled by FFI, if the header arg is a relative path but the file isn’t in working directory, also check the system header directories (e.g., /usr/include, /usr/local/include and /opt/local/include)
2. If the header is not given, identify the header name from the library name and use the previous checkbox point feature to locate it.