Hi Thomas, Greg, Steve & Reco, sorry for the late reply, but thank you all for the hints! :)
> Or skip the test by setting variable > am_cv_make_support_nested_variables to "yes" before running > configure: > > export am_cv_make_support_nested_variables=yes ./configure > > If skipping the test does reliably help, then the problem is with > that single test. If ./configure gets stuck some steps later, then > there is a general problem with the terminal or the shell which is > running in it. all done in tmux window with configure for GnuPG 2.2.11: user:/opt/git/gnupg-2.2.11$ ./configure checking for a BSD-compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking for a thread-safe mkdir -p... /bin/mkdir -p checking for gawk... gawk checking whether make sets $(MAKE)... yes checking whether make supports nested variables.. ~$ ps -ef | fgrep make user 27190 26927 0 21:37 pts/9 00:00:00 make -f - from GnuPG 2.2.11 configure: { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $am_make supports nested variables" >&5 $as_echo_n "checking whether $am_make supports nested variables... " >&6; } if ${am_cv_make_support_nested_variables+:} false; then : $as_echo_n "(cached) " >&6 else if $as_echo 'TRUE=$(BAR$(V)) BAR0=false BAR1=true V=1 am__doit: @$(TRUE) .PHONY: am__doit' | $am_make -f - >/dev/null 2>&1; then user:/opt/git/gnupg-2.2.11$ bash -x ./configure: + printf '%s\n' 'configure:3380: checking whether make supports nested variables' + printf %s 'checking whether make supports nested variables... ' checking whether make supports nested variables... + false + make -f - + printf '%s\n' 'TRUE=$(BAR$(V)) BAR0=false BAR1=true V=1 am__doit: @$(TRUE) .PHONY: am__doit' (end) user:/opt/git/gnupg-2.2.11$ export \ am_cv_make_support_nested_variables=yes user:/opt/git/gnupg-2.2.11$ ./configure -> worked: checking whether make supports nested variables... (cached) yes -- mlnl