bug#47159: 28.0.50; gnutls not recognized in build process without pkg-config

[Jean Louis]

Today I was switching from Hyperbola GNU/Linux-libre to Parabola
GNU/Linux-libre and some of first programs I wanted to build was
Emacs. I have not installed enough packages, but gnutls was installed.

Emacs' configure was complaining that gnutls cannot be found. But it was
there.

By chance I was thinkin that build process maybe uses pkg-config, so I
have installed pkg-config as package. The build process then continued
and could find gnutls.

In my opinion, there shall be a check for pkg-config if Emacs is using
such or requiring such to verify for existence of some software on the
system. It is misleading if it says it cannot find gnutls, but does not
say that pkg-config is missing which is supposed to detect the gnutls.



In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo version 
1.17.4, Xaw scroll bars)
 of 2021-03-15 built on protected.rcdrun.com
Repository revision: 5120b612f8520a855fc1819c3ebf86453c361e55
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12010000
Configured using:
 'configure --with-x-toolkit=lucid'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBSYSTEMD LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG RSVG
SOUND THREADS TIFF TOOLKIT_SCROLL_BARS X11 XDBE XIM XPM LUCID ZLIB

Important settings:
  value of $LC_ALL: en_US.UTF-8
  value of $LANG: de_DE.UTF-8
  value of $XMODIFIERS: @im=exwm-xim
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  shell-dirtrack-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr shell pcomplete comint ansi-color ring emacsbug
message rmc puny dired dired-loaddefs rfc822 mml mml-sec epa derived epg
epg-config gnus-util rmail rmail-loaddefs auth-source cl-seq eieio
eieio-core cl-macs eieio-loaddefs password-cache json map
text-property-search time-date subr-x seq byte-opt gv bytecomp
byte-compile cconv mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader cl-loaddefs cl-lib sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils iso-transl tooltip
eldoc electric uniquify ediff-hook vc-hooks lisp-float-type mwheel
term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode
lisp-mode prog-mode register page tab-bar menu-bar rfn-eshadow isearch
easymenu timer select scroll-bar mouse jit-lock font-lock syntax
facemenu font-core term/tty-colors frame minibuffer cl-generic cham
georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray
cl-preloaded nadvice button loaddefs faces cus-face macroexp files
window text-properties overlay sha1 md5 base64 format env code-pages
mule custom widget hashtable-print-readable backquote threads dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 56822 6744)
 (symbols 48 7505 1)
 (strings 32 21343 1938)
 (string-bytes 1 689068)
 (vectors 16 13811)
 (vector-slots 8 180271 10606)
 (floats 8 23 45)
 (intervals 56 227 0)
 (buffers 992 11))

-- 
Thanks,
Jean Louis
⎔ λ 🄯 𝍄 𝌡 𝌚