Bug#888394: GCC bootstrap comparison failure build the D frontend on alpha

Package: src:gcc-7
Version: 7.2.0-20
Severity: important

Seen with the last GCC 7 build from the branch on alpha,

make[4]: Entering directory '/<<PKGBUILDDIR>>/build'
make[5]: Entering directory '/<<PKGBUILDDIR>>/build'
rm -f stage_current
make[5]: Leaving directory '/<<PKGBUILDDIR>>/build'
Comparing stages 2 and 3
warning: gcc/cc1objplus-checksum.o differs
warning: gcc/cc1obj-checksum.o differs
Bootstrap comparison failure!
gcc/d/lexer.o differs
Makefile:23293: recipe for target 'compare' failed
make[4]: *** [compare] Error 1
make[4]: Leaving directory '/<<PKGBUILDDIR>>/build'
Makefile:23272: recipe for target 'stage3-bubble' failed
make[3]: *** [stage3-bubble] Error 2

last successful build was on 20180107 (r256317). No changes in the gdc code.