one more small patch for AIX in config/mh-ppc-aix in case $CC includes spaces.

for some reason in older gdb version we needed CC='gcc -isystem /usr/include'
shows that quoting problem.  will test if this still is needed (read: what's 
the real problem and a better fix, iff still needed at alll).



Harald Koenig
-- 
"I hope to die                                      ___       _____
before I *have* to use Microsoft Word.",           0--,|    /OOOOOOO\
Donald E. Knuth, 02-Oct-2001 in Tuebingen.        <_/  /  /OOOOOOOOOOO\
                                                    \  \/OOOOOOOOOOOOOOO\
                                                      \ OOOOOOOOOOOOOOOOO|//
Harald Koenig                                          \/\/\/\/\/\/\/\/\/
science+computing ag                                    //  /     \\  \
koenig@science-computing.de                            ^^^^^       ^^^^^
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