x86_64-w64-mingw32-g++: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/x86_64-w64-mingw32-g++ - from package: mingw64-gcc-c++

You may install the required package with command yum install {package}

Error in other languages:
x86_64-w64-mingw32-g++: bevel nie gevind nie
x86_64-w64-mingw32-g++: comandă negăsită
x86_64-w64-mingw32-g++: comando não encontrado
x86_64-w64-mingw32-g++: commande introuvable
x86_64-w64-mingw32-g++: command not found
x86_64-w64-mingw32-g++: käsku ei ole
x86_64-w64-mingw32-g++: không tìm thấy lệnh
x86_64-w64-mingw32-g++: komanda nerasta
x86_64-w64-mingw32-g++: Kommando nicht gefunden.
x86_64-w64-mingw32-g++: kommandot finns inte
x86_64-w64-mingw32-g++: komut yok
x86_64-w64-mingw32-g++: nie znaleziono polecenia
x86_64-w64-mingw32-g++: níor aimsíodh an t-ordú
x86_64-w64-mingw32-g++: no se encontró la orden
x86_64-w64-mingw32-g++: no s'ha trobat l'ordre
x86_64-w64-mingw32-g++: opdracht niet gevonden
x86_64-w64-mingw32-g++: parancs nem található
x86_64-w64-mingw32-g++: perintah tidak ditemukan
x86_64-w64-mingw32-g++: príkaz nenájdený
x86_64-w64-mingw32-g++: příkaz nenalezen
x86_64-w64-mingw32-g++: команда не найдена
x86_64-w64-mingw32-g++: командата не е открита
x86_64-w64-mingw32-g++: 命令找不到
x86_64-w64-mingw32-g++: コマンドが見つかりません