doc: Mention xdot.

* doc/guix.texi (Invoking guix graph): Mention xdot.  Remove a couple of
"| dot -Tpdf" in examples and add "| xdot".
(Invoking guix system): Likewise.
(Preparing to Use the Bootstrap Binaries): Likewise.

tests: Test 'guix show' with multiple packages.

* tests/guix-package-aliases.sh: Test 'guix show' with multiple packages.

guix package, show: Support multiple queries.

* guix/scripts/package.scm (process-query): Show multiple queries.
* guix/scripts/show.scm (guix-show): Reverse to display in order.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu: waylandpp: Update to 0.2.7.

* gnu/packages/freedesktop.scm (waylandpp): Update to 0.2.7.

gnu: wl-clipboard: Update to 2.0.0.

* gnu/packages/xdisorg.scm (wl-clipboard): Update to 2.0.0.
[source](uri): Add "v" prefix in tag reference.

gnu: capnproto: Update to 0.8.0.

* gnu/packages/serialization.scm (capnproto): Update to 0.8.0.

gnu: rng-tools: Update to 6.10.

* gnu/packages/linux.scm (rng-tools): Update to 6.10.
[arguments]: Add --without-rtlsdr in #:configure-flags.
[inputs]: Add OPENSSL, which is no longer optional.

gnu: lvm2: Update to 2.03.09.

* gnu/packages/linux.scm (lvm2): Update to 2.03.09.

gnu: libsecret: Update to 0.20.3.

* gnu/packages/gnome.scm (libsecret): Update to 0.20.3.

gnu: oniguruma: Do not build the static library.

* gnu/packages/textutils.scm (oniguruma)[arguments]: New field.

gnu: oniguruma: Update to 6.9.5-rev1.

* gnu/packages/textutils.scm (oniguruma): Update to 6.9.5-rev1.
[source](uri): Adjust for inconsistent URI when dashes are involved.

gnu: wxwidgets: Update to 3.0.5.1.

* gnu/packages/wxwidgets.scm (wxwidgets): Update to 3.0.5.1.

gnu: i3-wm: Update to 4.18.1.

* gnu/packages/wm.scm (i3-wm): Update to 4.18.1.

gnu: bitcoin: Fix test failure with Python 3.8.

* gnu/packages/patches/bitcoin-core-python-compat.patch: New file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/finance.scm (bitcoin-core)[source](patches): New field.

gnu: re2: Update to 2020-05-01.

* gnu/packages/regex.scm (re2): Update to 2020-05-01.
[source](modules, snippet): New fields.
* gnu/packages/chromium.scm (ungoogled-chromium)[arguments]: Add substitution
to adjust for re2 API change.
* gnu/packages/qt.scm (qtwebengine)[arguments]: Likewise.

gnu: OpenEXR: Update to 2.5.0.

* gnu/packages/patches/ilmbase-openexr-pkg-config.patch: Delete file.
* gnu/packages/patches/ilmbase-fix-test-arm.patch: New file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/graphics.scm (ilmbase): Update to 2.5.0.

gnu: samba: Update to 4.11.9.

* gnu/packages/samba.scm (samba): Update to 4.11.9.

gnu: flatpak: Update to 1.6.3.

* gnu/packages/package-management.scm (flatpak): Update to 1.6.3.
[arguments]: Enable tests; add --with-system-dbus-proxy to configure flags;
add "fix-tests" phase and replace "check" phase.
[native-inputs]: Add socat, dbus, python, which, and glibc-utf8-locales.
[inputs]: Add xdg-dbus-proxy.

gnu: git-annex: Add support for v4 of S3 support.

* gnu/packages/haskell-apps.scm (git-annex)[source]: Add patch.
* gnu/packages/patches/git-annex-S3v4.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.

gnu: Add rtl-443.

* gnu/packages/radio.scm (rtl-433): New variable.