mesa-private-llvm-config-64: 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/mesa-private-llvm-config-64 - from package: mesa-private-llvm-devel

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

Error in other languages:
mesa-private-llvm-config-64: bevel nie gevind nie
mesa-private-llvm-config-64: comandă negăsită
mesa-private-llvm-config-64: comando não encontrado
mesa-private-llvm-config-64: commande introuvable
mesa-private-llvm-config-64: command not found
mesa-private-llvm-config-64: käsku ei ole
mesa-private-llvm-config-64: không tìm thấy lệnh
mesa-private-llvm-config-64: komanda nerasta
mesa-private-llvm-config-64: Kommando nicht gefunden.
mesa-private-llvm-config-64: kommandot finns inte
mesa-private-llvm-config-64: komut yok
mesa-private-llvm-config-64: nie znaleziono polecenia
mesa-private-llvm-config-64: níor aimsíodh an t-ordú
mesa-private-llvm-config-64: no se encontró la orden
mesa-private-llvm-config-64: no s'ha trobat l'ordre
mesa-private-llvm-config-64: opdracht niet gevonden
mesa-private-llvm-config-64: parancs nem található
mesa-private-llvm-config-64: perintah tidak ditemukan
mesa-private-llvm-config-64: príkaz nenájdený
mesa-private-llvm-config-64: příkaz nenalezen
mesa-private-llvm-config-64: команда не найдена
mesa-private-llvm-config-64: командата не е открита
mesa-private-llvm-config-64: 命令找不到
mesa-private-llvm-config-64: コマンドが見つかりません