bug#31380: [core-updates] grub fails to build on i686-linux

[Mark H Weaver]

On the 'core-updates' branch, both 'grub' and 'grub-efi' fail to build
on i686-linux.  See below for the relevant excerpt from the build log
of 'grub-efi', but the error is the same for both.

  https://hydra.gnu.org/build/2675846
  https://hydra.gnu.org/build/2684033

      Mark

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gcc -DHAVE_CONFIG_H -I. -I..  -Wall -W  -DGRUB_MACHINE_EFI=1 
-DGRUB_MACHINE=I386_EFI -m32 -nostdinc -isystem 
/gnu/store/w55k6qc17s6nf7rv4agap9lsas4hb50l-gcc-5.5.0-lib/lib/gcc/i686-unknown-linux-gnu/5.5.0/include
 -I../include -I../include -DGRUB_FILE=\"lib/i386/relocator.c\" -I. -I. -I.. 
-I.. -I../include -I../include -I../grub-core/lib/libgcrypt-grub/src/    
-D_FILE_OFFSET_BITS=64 -Os -Wall -W -Wshadow -Wpointer-arith -Wundef 
-Wchar-subscripts -Wcomment -Wdeprecated-declarations -Wdisabled-optimization 
-Wdiv-by-zero -Wfloat-equal -Wformat-extra-args -Wformat-security -Wformat-y2k 
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int -Wmain 
-Wmissing-braces -Wmissing-format-attribute -Wmultichar -Wparentheses 
-Wreturn-type -Wsequence-point -Wshadow -Wsign-compare -Wswitch -Wtrigraphs 
-Wunknown-pragmas -Wunused -Wunused-function -Wunused-label -Wunused-parameter 
-Wunused-value  -Wunused-variable -Wwrite-strings -Wnested-externs 
-Wstrict-prototypes -g -Wredundant-decls -Wmissing-prototypes 
-Wmissing-declarations  -Wextra -Wattributes -Wendif-labels -Winit-self 
-Wint-to-pointer-cast -Winvalid-pch -Wmissing-field-initializers -Wnonnull 
-Woverflow -Wvla -Wpointer-to-int-cast -Wstrict-aliasing -Wvariadic-macros 
-Wvolatile-register-var -Wpointer-sign -Wmissing-include-dirs 
-Wmissing-prototypes -Wmissing-declarations -Wformat=2 -march=i386 -m32 
-falign-jumps=1 -falign-loops=1 -falign-functions=1 -freg-struct-return 
-mno-mmx -mno-sse -mno-sse2 -mno-sse3 -mno-3dnow -msoft-float 
-fno-dwarf2-cfi-asm -mno-stack-arg-probe -fno-asynchronous-unwind-tables 
-fno-unwind-tables -Qn -fno-stack-protector -Wtrampolines -Werror   
-ffreestanding   -MT lib/i386/relocator_module-relocator.o -MD -MP -MF 
lib/i386/.deps-core/relocator_module-relocator.Tpo -c -o 
lib/i386/relocator_module-relocator.o `test -f 'lib/i386/relocator.c' || echo 
'./'`lib/i386/relocator.c
lib/i386/relocator64.S: Assembler messages:
lib/i386/relocator64.S:66: Error: unknown pseudo-op: `.code64'
lib/i386/relocator64.S:74: Error: bad register name `%rax'
lib/i386/relocator64.S:88: Error: bad register name `%rsp'
lib/i386/relocator64.S:98: Error: bad register name `%rax'
lib/i386/relocator64.S:132: Error: bad register name `%rip)'
make[3]: *** [Makefile:28996: lib/i386/relocator_module-relocator64.o] Error 1
make[3]: *** Waiting for unfinished jobs....
mv -f lib/.deps-core/crypto_module-crypto.Tpo 
lib/.deps-core/crypto_module-crypto.Po
mv -f lib/i386/.deps-core/relocator_module-relocator.Tpo 
lib/i386/.deps-core/relocator_module-relocator.Po
mv -f fs/.deps-core/xfs_module-xfs.Tpo fs/.deps-core/xfs_module-xfs.Po
make[3]: Leaving directory 
'/tmp/guix-build-grub-efi-2.02.drv-0/grub-2.02/grub-core'
make[2]: *** [Makefile:23531: all] Error 2
make[2]: Leaving directory 
'/tmp/guix-build-grub-efi-2.02.drv-0/grub-2.02/grub-core'
make[1]: *** [Makefile:10904: all-recursive] Error 1
make[1]: Leaving directory '/tmp/guix-build-grub-efi-2.02.drv-0/grub-2.02'
make: *** [Makefile:3130: all] Error 2
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