gnu: z3: Update to 4.8.9.

* gnu/packages/maths.scm (z3): Update to 4.8.9.

Signed-off-by: Christopher Baines <mail@cbaines.net>

gnu: git: Add phase to restore hooks shebang.

Fixes <https://bugs.gnu.org/25508>.

* gnu/packages/version-control.scm (git)[arguments]: New phase
restore-sample-hooks-shebang.

.dir-locals.el: Add upstream report link.

Follow up from 1d6e7732b163c9e945c9e5b32c726fe3b5f09c3a.

* .dir-locals.el: Modify comment to point at the report to bug-gnu-emacs.

gnu: grub: Cross-compile for mips64el-linux.

* gnu/packages/bootloaders.scm (grub)[arguments]: Add custom phase to
set BUILD_FREETYPE_* flags.
[native-inputs]: Add freetype.

gnu: grub: Don't run tests when cross compiling.

* gnu/packages/bootloaders.scm (grub)[arguments]: Skip tests when
cross-compiling.

gnu: Add emacs-boon.

* gnu/packages/emacs-xyz.scm (emacs-boon): New variable.

Signed-off-by: Nicolas Goaziou <mail@nicolasgoaziou.fr>

gnu: Add emacs-modalka.

* gnu/packages/emacs-xyz.scm (emacs-modalka): New variable.

Signed-off-by: Nicolas Goaziou <mail@nicolasgoaziou.fr>

gnu: emacs-matrix-client: Update to 0.0.0-5.59c7924.

* gnu/packages/emacs-xyz.scm (emacs-matrix-client): Update to 0.0.0-5.59c7924.

Signed-off-by: Nicolas Goaziou <mail@nicolasgoaziou.fr>

.dir-locals.el: Use setq-local on guix-directory.

* .dir-locals.el: Use setq-local on guix-directory.  While a problem with
using setq hasn't been identified, this seems like good hygiene.

.dir-locals.el: Prevent errors if .dir-locals.el isn't found.

While this repo should presumably always have a .dir-locals.el
by the nature of this file itself, it seems that this behavior "leaks".
See added comment for more details on the fix to this strange bug,
which is likely an upstream emacs or vc-mode issue.

Thanks to Miguel Ángel Arruga Vivas and Maxim Cournoyer for helping
investigate this problem.

* .dir-locals.el: Don't error out if .dir-locals.el isn't found.

gnu: icedove: Update to 78.4.3.

* gnu/packages/gnuzilla.scm (icedove): Update to 78.4.3.

gnu: gcc-vc4: Update to commit 0fe4b83897341742f9df65797474cb0feab4b377.

* gnu/packages/patches/gcc-6-fix-buffer-size.patch: New file.
* gnu/packages/patches/gcc-6-fix-isl-includes.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/embedded.scm (gcc-vc4): Update to commit
0fe4b83897341742f9df65797474cb0feab4b377.
[source]: Add the patches from above.

gnu: pzstd: Cross compile.

* gnu/packages/compression.scm (pzstd)[arguments]: use cc-for-target,
cxx-for-target in make-flags.
[native-inputs]: Only use googletest when compiling natively.
[inputs]: Add googletest when cross compiling.

gnu: zstd: Cross compile.

* gnu/packages/compression.scm (zstd)[arguments]: When targeting another
system use cc-for-target in make-flags.

gnu: bsdiff: Cross compile.

* gnu/packages/compression.scm (bsdiff)[arguments]: Use cc-for-target in
make-flags.

gnu: squashfs-tools: Cross compile.

* gnu/packages/compression.scm (squashfs-tools)[arguments]: Use
cc-for-target in make-flags.

gnu: lz4: Cross compile.

* gnu/packages/compression.scm (lz4)[arguments]: When targeting another
system use cc-for-target in make-flags.

gnu: bam: Cross-compile.

* gnu/packages/build-tools.scm (bam)[arguments]: Use cc-for-target in
make-flags.

gnu: lua: Cross compile.

* gnu/packages/lua.scm (lua)[arguments]: Use cc-for-target in
make-flags. Set SYSLIBS to include readline.

gnu: premake4: Cross compile.

* gnu/packages/build-tools.scm (premake4)[arguments]: Use cc-for-target
in make-flags.