xtensa-linux-gnu-gcc: 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/xtensa-linux-gnu-gcc - from package: gcc-xtensa-linux-gnu

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

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