winman | basic yet powerful window manager in go

I have a program (cpp) with many classes. Every class is in separate source file (.h + .cpp).
How can I split the compiled program into multiple files (instead of one big executable file)?
Let's say, one file for every class (same as the code structure).
So that every time there is change in a specific class, I compile only that class, and replace the specific compiled file related to that class.
(Something similar to .DLL files in Windows.)

Example from real life:
I am making TUI interface for managing mysql.
I would like to create mysql text editor (TUI) with ncurses.

the code (class) for creating and managing single window object is in 'textWin.cpp' + 'textWin.h'

the code (class) for managing multiple windows, by creating windows objects from previous class is in winMan.cpp winMan.h

the code (class) for managing mysql database is in : mysql.cpp mysql.h

and so on...

so, I have the following files:
MyProgram.cpp
- winMan.cpp + winMan.h
- textWin.cpp + textWin.h
- mysql.cpp + mysql.h
- ..
- ..

After g++ compilation, I get one executable file, './MyProgram' (size about 15Mb.) which I deliver to all my customers (1000's of them).

I Just found a typo in textWin.cpp, I fixed it, and I told to all customers that there is an update... all of them need to download one big 15Mb file, this consumes allot of bandwidth and server resources, for just a small update.
Is there a way to send to all my customers smaller file, that contains only the compiled code for textWin class ?

I use g++ on Centos7