curl up to 7.45.0 could be built without perl and GNU make (BSD make was fine).
In 7.46.0, the zsh support in scripts/ made both of these tools necessary.
gmake: Entering directory '/scratch/www/curl/work/curl-7.46.0/scripts'
/usr/pkg/bin/perl zsh.pl > _curl
curl: not found
Use of uninitialized value $opts_str in scalar chomp at zsh.pl line 16.
Use of uninitialized value $opts_str in concatenation (.) or string at zsh.pl line 18.