build issue - gmp

Also commented in #38 (I searched issues for gmp and that was only result)

On Ubuntu 20.04 with a git clone done a few hours ago:

patching file gcc/configure.ac
Reversed (or previously applied) patch detected! Assume -R? [n]
Apply anyway? [n]
Skipping patch.
1 out of 1 hunk ignored -- saving rejects to file gcc/configure.ac.rej
patching file gcc/doc/invoke.texi
Reversed (or previously applied) patch detected! Assume -R? [n]
Apply anyway? [n]
Skipping patch.
4 out of 4 hunks ignored -- saving rejects to file gcc/doc/invoke.texi.rej
patching file gcc/ira.c
Reversed (or previously applied) patch detected! Assume -R? [n]
Apply anyway? [n]
Skipping patch.
1 out of 1 hunk ignored -- saving rejects to file gcc/ira.c.rej
patching file gcc/testsuite/gcc.c-torture/compile/limits-externdecl.c
Reversed (or previously applied) patch detected! Assume -R? [n]
Apply anyway? [n]
Skipping patch.
1 out of 1 hunk ignored -- saving rejects to file gcc/testsuite/gcc.c-torture/compile/limits-externdecl.c.rej
patching file gcc/testsuite/lib/target-supports.exp
Hunk #1 succeeded at 7966 (offset 18 lines).
patching file gcc/tree.h
Reversed (or previously applied) patch detected! Assume -R? [n]
Apply anyway? [n]
Skipping patch.
1 out of 1 hunk ignored -- saving rejects to file gcc/tree.h.rej

• mv gmp-5.0.2 gcc/gmp
  mv: cannot stat 'gmp-5.0.2': No such file or directory
  root@buildbox:/subo/Tooling/src/team-sweng/cross-compile/arduino-avr/toolchain-avr#
  root@buildbox:/subo/Tooling/src/team-sweng/cross-compile/arduino-avr/toolchain-avr#

I did a git clone, copy/paste of the various bash script invokes from readme.md.