[BUG] default CXXFLAGS on powerpc

[Keri Harris]

configure sets incorrect CXXFLAGS on powerpc. A vanilla './configure && make' 
produces:

<snip>
gmake[2]: Entering directory 
`/home/keri/mozart-scm-2008-06-28/trunk/mozart/platform/dss'
g++ -march=powerpc -mtune=powerpc -O3 -fomit-frame-pointer -funsigned-char -I. -I/home/keri/mozart-scm-2008-06-28/trunk/mozart/platform/dss/include -fno-exceptions -Winline -Weffc++ -Wall -Wold-style-cast -Woverloaded-virtual -Wshadow   -c -o 
base.o /home/keri/mozart-scm-2008-06-28/trunk/mozart/platform/dss/src/base.cc
cc1plus: error: unrecognized command line option "-march=powerpc"
gmake[2]: *** [base.o] Error 1

I don't think g++ on PowerPC/RS6000 has a "-march" flag.

Thanks

Keri