How to fix 'error trying to exec 'cc1obj': execvp: No such file or directory
You need to install the corresponding Objective-C++ cross compiler package, either from your favorite GUI package manager or via the command line using
sudo apt install gobjc++-mingw-w64
This should install both gobjc++-mingw-w64-i686 and gobjc++-mingw-w64-x86-64 allowing you to build Objective-C++ code targeting both 32-bit and 64-bit Windows platforms.