sparc port still fails bootstrap on sparc-sun-solaris28 (sparcv9 bootstraps)

[Brad Lucier]

For some reason configure-target-libstdc++-v3 doesn't work on
sparc-sun-solaris2.8:

checking for thread model used by GCC... posix
checking for exception model to use... configure: error: unable to detect exception model
make[1]: *** [configure-target-libstdc++-v3] Error 1
make[1]: Leaving directory `/export/u3/lucier/programs/gcc/gcc-3.1/objdir'
make: *** [bootstrap] Error 2

For some reason the sparcv9-sun-solaris28 bootstrap doesn't 
have this problem.

Brad