Fix for building with cereal>=1.3.1.
This patch comes from Gentoo:
 portage/media-gfx/prusaslicer/files/prusaslicer-2.5.0_rc1-cereal-1.3.1.patch

--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -127,7 +127,7 @@
     set_target_properties(PrusaSlicer PROPERTIES OUTPUT_NAME "prusa-slicer")
 endif ()

-target_link_libraries(PrusaSlicer libslic3r cereal)
+target_link_libraries(PrusaSlicer libslic3r libcereal)

 if (APPLE)
 #    add_compile_options(-stdlib=libc++)
--- a/src/slic3r/CMakeLists.txt
+++ b/src/slic3r/CMakeLists.txt
@@ -260,7 +260,7 @@

 encoding_check(libslic3r_gui)

-target_link_libraries(libslic3r_gui libslic3r avrdude cereal imgui GLEW::GLEW OpenGL::GL hidapi libcurl ${wxWidgets_LIBRARIES})
+target_link_libraries(libslic3r_gui libslic3r avrdude libcereal imgui GLEW::GLEW OpenGL::GL hidapi libcurl ${wxWidgets_LIBRARIES})

 if (MSVC)
     target_link_libraries(libslic3r_gui Setupapi.lib)
--- a/src/libslic3r/CMakeLists.txt
+++ b/src/libslic3r/CMakeLists.txt
@@ -395,7 +395,7 @@
 target_link_libraries(libslic3r
     libnest2d
     admesh
-    cereal
+    libcereal
     libigl
     miniz
     boost_libs
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -446,6 +446,12 @@

 # Find the Cereal serialization library
 find_package(cereal REQUIRED)
+add_library(libcereal INTERFACE)
+if (NOT TARGET cereal::cereal)
+    target_link_libraries(libcereal INTERFACE cereal)
+else()
+    target_link_libraries(libcereal INTERFACE cereal::cereal)
+endif()

 # l10n
 set(L10N_DIR "${SLIC3R_RESOURCES_DIR}/localization")
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<div class='path'>path: <a href='/guix/log/?id=2e99cb15e6483c6c0a2335173ad84e0d540f3fad'>root</a>/<a href='/guix/log/gnu?id=2e99cb15e6483c6c0a2335173ad84e0d540f3fad'>gnu</a>/<a href='/guix/log/gnu/bootloader?id=2e99cb15e6483c6c0a2335173ad84e0d540f3fad'>bootloader</a>/<a href='/guix/log/gnu/bootloader/depthcharge.scm?id=2e99cb15e6483c6c0a2335173ad84e0d540f3fad'>depthcharge.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/bootloader/depthcharge.scm?id=2e99cb15e6483c6c0a2335173ad84e0d540f3fad&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-05-20 08:30:35 -0400'>2020-05-20</span></td><td><a href='/guix/commit/gnu/bootloader/depthcharge.scm?id=b460ba7992a0b4af2ddb5927dcf062784539ef7b'>bootloader: grub: Allow booting from a Btrfs subvolume.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/bootloader/grub.scm (strip-mount-point): Remove procedure.
(normalize-file): Add procedure.
(grub-configuration-file): New BTRFS-SUBVOLUME-FILE-NAME parameter.  When
defined, prepend its value to the kernel and initrd file names, using the
NORMALIZE-FILE procedure.  Adjust the call to EYE-CANDY to pass the
BTRFS-SUBVOLUME-FILE-NAME argument.  Normalize the KEYMAP file as well.
(eye-candy): Add a BTRFS-SUBVOLUME-FILE-NAME parameter, and use it, along with
the NORMALIZE-FILE procedure, to normalize the FONT-FILE and IMAGE nested
variables.  Adjust doc.
* gnu/bootloader/depthcharge.scm (depthcharge-configuration-file): Adapt.
* gnu/bootloader/extlinux.scm (extlinux-configuration-file): Likewise.
* gnu/system/file-systems.scm (btrfs-subvolume?)
(btrfs-store-subvolume-file-name): New procedures.
* gnu/system.scm (operating-system-bootcfg): Specify the Btrfs
subvolume file name the store resides on to the
`operating-system-bootcfg' procedure, using the new
BTRFS-SUBVOLUME-FILE-NAME argument.
* doc/guix.texi (File Systems): Add a Btrfs subsection to document the use of
subvolumes.
* gnu/tests/install.scm (%btrfs-root-on-subvolume-os)
(%btrfs-root-on-subvolume-os-source)
(%btrfs-root-on-subvolume-installation-script)
(%test-btrfs-root-on-subvolume-os): New variables.
</span></span></td><td>Maxim Cournoyer</td></tr>