mbed-os-to-arduino "mbed new" doesn't create the mbed-os folder

[JAndrassy]

mbed new doesn't clone mbed-os into /tmp/mbed-os-program (maybe because it is a non standard location).
then the rest of the script doesn't work.
this PR fixes it for link to local repo, so if used with -r.

additionally the script requires

export PATH=$PATH:~/.arduino15/packages/arduino/tools/arm-none-eabi-gcc/7-2017q4/bin

to finish successful, but I guess it is not right to put it into the script

[facchinm]

Hi Juraj, can you check which version of mbed-cli is installed in your system? Normally mbed new also clones the latest branch from https://github.com/ARMmbed/mbed-os (we package the cores with this method). For the toolchain, anything between gcc 9 and 10 is better, and as you notice should be already available in the user's PATH.

[JAndrassy]

I have version 1.10.5 on Linux Mint
It doesn't even create the mbed-os folder

juraj@nuc:~$ mbed new mbed-test --verbose
[mbed] Working path "/home/juraj" (directory)
[mbed] Exec "git init /home/juraj/mbed-test -q" in "/home/juraj"
[mbed] Creating new program "mbed-test" (git)