Fixes <https://bugs.gnu.org/27551>.
Reported by Leo Famulari <leo@famulari.name>.
This reinstates the following commits:
e3ddb1e83 * gnu: guile-cairo: Switch to Guile 2.2.
ae5c6ef39 * gnu: guile-gnome: Update to 2.16.5.
0fd8013fc * gnu: guile-rsvg: Update to commit 05c6a2fd.
66b9183c4 * gnu: guile-lib: Switch to Guile 2.2.
and adds the following changes:
* gnu/bootloader/grub.scm (svg->png): Add 'package->derivation' call for
GUILE-2.2. Pass #:guile-for-build to 'gexp->derivation'.
* gnu/build/svg.scm (svg->png): Add 'em' and 'ex' to the 'let-values'
form to account for all the values returned by
'rsvg-handle-get-dimensions', which Guile 2.2 does not truncate.
* gnu/packages/gtk.scm (guile-rsvg): Update to commit 05c6a2fd.
[source](url): Change to gitlab.com.
(snippet): Use @GUILE_EFFECTIVE_VERSION@ instead of "2.0".
* gnu/packages/patches/guile-rsvg-pkgconfig.patch: Use
"$GUILE_EFFECTIVE_VERSION" instead of "2.0".
* gnu/packages/gtk.scm (guile-rsvg): New variable.
* gnu/packages/patches/guile-rsvg-pkgconfig.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
