bug#37197: 26.2; eww broken

[Andreas Röhler]

M-x eww RET SOMEURL RET
results in error:

Debugger entered--Lisp error: (error "This function requires Emacs to be 
compiled with libxml2")
  signal(error ("This function requires Emacs to be compiled with 
libxml2"))
  error("This function requires Emacs to be compiled with libxml2")...

However, when trying to install libxml2, being told it exists:

»libxml2« ist bereits in der angeforderten Version 
(2.9.4+dfsg1-7ubuntu3) installiert.

File config.log has the following:

configure:16473: checking for LIBXML2
configure:16480: $PKG_CONFIG --exists --print-errors "libxml-2.0 > 2.6.17"
Package libxml-2.0 was not found in the pkg-config search path.
Perhaps you should add the directory containing `libxml-2.0.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libxml-2.0' found
configure:16483: $? = 1
configure:16497: $PKG_CONFIG --exists --print-errors "libxml-2.0 > 2.6.17"
Package libxml-2.0 was not found in the pkg-config search path.
Perhaps you should add the directory containing `libxml-2.0.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libxml-2.0' found
configure:16500: $? = 1
configure:16514: result: no
No package 'libxml-2.0' found

In GNU Emacs 26.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 2.24.32)
 of 2019-07-11
Windowing system distributor 'The X.Org Foundation', version 11.0.12004000
System Description:    Ubuntu 19.04

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Contacting host: youtube.com:80
error in process filter: eww-display-html: This function requires Emacs 
to be compiled with libxml2
error in process filter: This function requires Emacs to be compiled 
with libxml2

Configured using:
 'configure --with-mailutils --with-modules'

Configured features:
XPM JPEG TIFF GIF PNG SOUND GSETTINGS GLIB NOTIFY GNUTLS FREETYPE XFT
ZLIB TOOLKIT_SCROLL_BARS GTK2 X11 XDBE XIM MODULES THREADS

Important settings:
  value of $LANG: de_DE.UTF-8
  locale-coding-system: utf-8-unix

Major mode: eww

Minor modes in effect:
  tooltip-mode: t
  global-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
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message dired dired-loaddefs rfc822 mml
mml-sec epa derived epg epg-config mm-decode mm-bodies mm-encode
mailabbrev gmm-utils mailheader sendmail network-stream starttls
url-http tls gnutls mail-parse rfc2231 url-gw nsm rmc url-cache url-auth
eww easymenu puny mm-url gnus nnheader gnus-util rmail rmail-loaddefs
rfc2047 rfc2045 ietf-drums mail-utils wid-edit mm-util mail-prsvr
url-queue url url-proxy url-privacy url-expand url-methods url-history
url-cookie url-domsuf url-util url-parse auth-source cl-seq eieio
eieio-core cl-macs eieio-loaddefs password-cache url-vars mailcap shr
svg xml seq byte-opt gv bytecomp byte-compile cconv dom browse-url
format-spec cl-loaddefs cl-lib elec-pair time-date mule-util 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 menu-bar rfn-eshadow isearch timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame 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 minibuffer cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote threads inotify dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 236308 10497)
 (symbols 48 45574 2)
 (miscs 40 58 123)
 (strings 32 93210 2518)
 (string-bytes 1 1564155)
 (vectors 16 17955)
 (vector-slots 8 558579 11112)
 (floats 8 73 44)
 (intervals 56 214 0)
 (buffers 992 15))