Make DEVELOPER more more flexible with DEVOPTS

This is a v4 and replacement of gitster/nd/warn-more-for-devs. I'm sending this with Duy's blessing.

The first two patches are the same, except for one trivial s/faimily/family/ typo fix.

The third patch in gitster/nd/warn-more-for-devs ("Makefile: add EAGER_DEVELOPER mode") is gone, instead there's now a DEVOPTS option. The 3/4 and 4/4 add a way to turn off -Werror & the -Wextra suppression, respectively.

Duy was right in [1] that this is a much better and extensible way of doing this than my "Makefile: untangle DEVELOPER and -Werror" patch.

Most of 3/4 & 4/4 are just tweaked from [email protected]:pclouds/git.git pclouds/more-warnings and combined with my previous 4/3 patch[2].

I changed the "no-suppression" name in Duy's WIP patch to "extra-all", and "gentle" to "no-error". I think those are cleare,r and leave things more open to future expansion, e.g. if we'd like pedantic-all.

1. https://public-inbox.org/git/CACsJy8CyB0igY365NMkswSgAi9_rf+XBOMQyJ7XW6iQxQiCEyQ@mail.gmail.com/
2. https://public-inbox.org/git/[email protected]/

Nguyễn Thái Ngọc Duy (2):
connect.c: mark die_initial_contact() NORETURN
Makefile: detect compiler and enable more warnings in DEVELOPER=1

Ævar Arnfjörð Bjarmason (2):
Makefile: add a DEVOPTS to suppress -Werror under DEVELOPER
Makefile: add a DEVOPTS to get all of -Wextra

 Makefile        | 31 +++++++++++++++++++----------
 config.mak.dev  | 42 +++++++++++++++++++++++++++++++++++++++
 connect.c       |  2 +-
 detect-compiler | 53 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 117 insertions(+), 11 deletions(-)
 create mode 100644 config.mak.dev
 create mode 100755 detect-compiler

2.17.0.290.gded63e768a