bug#49949: [core-updates]: Blender fails to build

[Leo Famulari]

On core-updates-frozen, Blender fails to build like this:

------
[ 45%] Building C object 
source/blender/imbuf/CMakeFiles/bf_imbuf.dir/intern/scaling.c.o
cd /tmp/guix-build-blender-2.92.0.drv-0/build/source/blender/imbuf && 
/gnu/store/r0y0ll80a350fmfjdpb6m97fk8cm2af1-gcc-10.3.0/bin/gcc -DNDEBUG 
-DWITH_ASSERT_ABORT -DWITH_AVI -DWITH_CINEON -DWITH_DDS -DWITH_FFMPEG 
-DWITH_HDR -DWITH_OPENEXR -DWITH_OPENGL -DWITH_OPENIMAGEIO -DWITH_OPENJPEG 
-DWITH_TIFF -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE 
-D__LITTLE_ENDIAN__ -D__MMX__ -D__SSE2__ -D__SSE__ 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/source/blender/imbuf 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/source/blender/blenkernel 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/source/blender/blenlib 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/source/blender/blenloader 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/source/blender/gpu 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/source/blender/makesdna 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/source/blender/makesrna 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/source/blender/sequencer 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/intern/guardedalloc 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/intern/memutil 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/source/blender/io/avi 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/intern/ffmpeg 
-I/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/intern/opencolorio 
-isystem 
/gnu/store/zw0qsbf5fk6hk556mcg1dn7vyl6nsl8x-openjpeg-2.4.0/include/openjpeg-2.4 
-isystem /usr/include -Wall -Wcast-align -Werror=implicit-function-declaration 
-Werror=return-type -Werror=vla -Wstrict-prototypes -Wmissing-prototypes 
-Wno-char-subscripts -Wno-unknown-pragmas -Wpointer-arith -Wunused-parameter 
-Wwrite-strings -Wlogical-op -Wundef -Winit-self -Wmissing-include-dirs 
-Wno-div-by-zero -Wtype-limits -Wformat-signedness -Wrestrict -Wnonnull 
-Wabsolute-value -Wuninitialized -Wredundant-decls -Wshadow 
-Wno-error=unused-but-set-variable -Wimplicit-fallthrough=5  -fopenmp 
-std=gnu11 -msse -pipe -fPIC -funsigned-char -fno-strict-aliasing 
-ffp-contract=off -msse2 
-fmacro-prefix-map="/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/"="" 
-fmacro-prefix-map="/tmp/guix-build-blender-2.92.0.drv-0/build/"="" 
-Wno-maybe-uninitialized -O2 -g -DNDEBUG -MD -MT 
source/blender/imbuf/CMakeFiles/bf_imbuf.dir/intern/scaling.c.o -MF 
CMakeFiles/bf_imbuf.dir/intern/scaling.c.o.d -o 
CMakeFiles/bf_imbuf.dir/intern/scaling.c.o -c 
/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/source/blender/imbuf/intern/scaling.c
/tmp/guix-build-blender-2.92.0.drv-0/blender-2.92.0/source/blender/imbuf/intern/openexr/openexr_api.cpp:35:10:
 fatal error: Iex.h: No such file or directory
   35 | #include <Iex.h>
      |          ^~~~~~~
compilation terminated.
make[2]: *** 
[source/blender/imbuf/intern/openexr/CMakeFiles/bf_imbuf_openexr.dir/build.make:79:
 
source/blender/imbuf/intern/openexr/CMakeFiles/bf_imbuf_openexr.dir/openexr_api.cpp.o]
 Error 1
make[2]: Leaving directory '/tmp/guix-build-blender-2.92.0.drv-0/build'
make[1]: *** [CMakeFiles/Makefile2:5942: 
source/blender/imbuf/intern/openexr/CMakeFiles/bf_imbuf_openexr.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
cc1: warning: /usr/include: No such file or directory [-Wmissing-include-dirs]
------

Any ideas?