build-system/gnu: Really ignore the return value of phases.

This is a followup to 04baa011e9122205009d6d5f15b8162bf6f3fb8a.

* guix/build/gnu-build-system.scm (gnu-build): Really ignore the return
value of PROC.  Wrap PROC call in 'with-throw-handler'.  Add
'end-of-phase' procedure and use it.

gnu: tar: Update to 1.33.

* gnu/packages/base.scm (tar): Update to 1.33.

gnu: findutils: Update to 4.8.0.

* gnu/packages/base.scm (findutils): Update to 4.8.0.
[source](patches): Remove "findutils-test-rwlock-threads.patch".
* gnu/packages/patches/findutils-test-rwlock-threads.patch: Remove.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/commencement.scm (findutils-boot0)[arguments]: Add
'skip-fnmatch-test' phase.

gnu: ed: Update to 1.17.

* gnu/packages/ed.scm (ed): Update to 1.17.

gnu: zstd: Add missing slash in 'libzstd.pc'.

Fixes a regression introduced in
959a397d220ad49b5193feb84b036220313fb9c7, whereby directory names in
'libzstd.pc' would lack a slash after $prefix.

* gnu/packages/compression.scm (zstd)[arguments]: In
'adjust-library-locations' phase, add trailing slash for $prefix in .pc
file.

gnu: texlive-bin: Patch shell commands in scripts.

* gnu/packages/tex.scm (texlive-bin)[phases]{patch-scripts}: New phase.

gnu: texlive-bin: Fix the tlmgr utility.

Previously, it would error out, not finding its Perl modules, and later not
finding config.guess.  This utility is useful to query the local TeX Live
package database (texlive.tlpdb).

(texlive-bin)[inputs]{config}: New input.
[phases]{postint}: Add a symlink to the 'config.guess' script.  Patch the
tlmgr.pl script so that it can find its Perl modules and other resources.

gnu: texlive-bin: Unpack the texlive-scripts and texlive-extra inputs early.

This allows the sources to processed normally by the other phases such as
patch-source-shebangs.

* gnu/packages/tex.scm (texlive-bin)[arguments]: Specify #:modules.
[phases]{unpack-texlive-extra, unpack-texlive-scripts}: New phases.
{postint}: Move the unpacking of the texlive-extra and texlive-scripts inputs
to the above newly added phases.  The installation of these extra directories
now simply uses copy-recursively.

gnu: texlive-bin: Fix indentation.

* gnu/packages/tex.scm (texlive-bin): Fix indentation.

gnu: texlive-bin: Replace python-2 by python.

* gnu/packages/tex.scm (texlive-bin)[inputs]: Replace python-2 by python.

build-system/texlive: Allow specifying SVN references with a single component.

This is the case for macros (formats), for which the TeX Directory Structure
specifies to be located at the root of the source tree directly.

* guix/build-system/texlive.scm (texlive-ref): Make the ID parameter
optional.  Update doc.

gnu: texlive-texmf: Replace python-2 by python.

* gnu/packages/tex.scm (texlive-texmf)[inputs]: Replace python-2 by python.

gnu: Add docbook-utils.

* gnu/packages/docbook.scm (docbook-utils): New variable.

gnu: Add texlive-jadetex.

* gnu/packages/tex.scm (texlive-jadetex): New variable.

gnu: Add texlive-xmltex.

* gnu/packages/tex.scm (texlive-xmltex): New variable.

gnu: texlive-wasysym: Update synopsis and description.

* gnu/packages/tex.scm (texlive-wasysym)[synopsis]: Refer to the font by
'wasy', not WASY2.
[description]: Likewise.  Use code ornaments for the LaTeX package names.

gnu: Add texlive-wasy.

* gnu/packages/tex.scm (texlive-wasy): New variable.

gnu: texlive-stmaryrd: Actually include the fonts.

* gnu/packages/tex.scm (texlive-stmaryrd): Rewrite package to inherit from a
simple-texlive-template package, so that fonts resources as listed in the
texlive.tlpdb database are retrieved and installed.
[arguments]: Adapt to use with the inherited template.
{chdir}: New phase.

gnu: Add texlive-helvetic.

* gnu/packages/tex.scm (texlive-helvetic): New variable.

gnu: Add texlive-courier.

* gnu/packages/tex.scm (texlive-courier): New variable.