Build #3579 (Jan 17, 2021 10:10:13 PM)

1. Improve target setup in makefiles (detail / cgit)
2. split out library and feature building macros (detail / cgit)
3. remove stray tab in hts makefile to fix amigaos3 build (detail / cgit)

Started by upstream project netsurf build number 5228
originally caused by:

• Started by an SCM change

• origin/master