2009-09-01  #i104566# also use syslibroot/isysroot for external components
2009-08-28  #i104568# clean up duplicated definitions of OBJCXXFLAGS
2009-08-28  #i104567# add ccache-detection to configure (to skip to objcxx-flags)
2009-08-28  #i104566# use Mac OS X 10.4-SDK to ensure backwards compatibility
use MACOSX_DEPLOYMENT_TARGET and sysroot/syslibroot switches
ignore "-isysroot /Developer/..." arguments for OOo's cpp