Control: affects -1 src:sagemath
A FTBFS in sagemath boiled down to gf2x violating
the amd64 baseline by building with
"-msse2 -msse3 -mssse3 -msse4.1 -mpclmul".
The same problem exists on i386 with
"-msse2 -msse3 -mssse3".
gf2x 1.1-2 has similar problems by building with
"-msse2 -mpclmul" if supported during the build,
and building with "-msse2" on i386.
gf2x must not ever set any of these flags
(-msse2 on amd64 is harmless since it is
already enabled by default, but therefore