[CMake] XCode 2.1 partial support

[Mathieu Malaterre]

> No and No.  Xcode is tied closely to the OS.  2.0/2.1 requires OS 10.4
> and will not work on 10.3.  1.5 requires 10.3 and will not work on 10.4.
> 


Sean,

   Could you also check that Xcode 21 is compatible with gcc3.3. I could not figure out a way to the following:

$ export CC=/usr/bin/gcc-3.3
$ export CXX=/usr/bin/g++-3.3
$ /Users/Malaterre/Dashboards/MyTests/CMake-gcc/bin/cmake ../CMake -GXcode15 
<snip>
CompileC CMAKE_TRY_COMPILE.build/Debug/cmTryCompileExec.build/Objects-normal/ppc/testCCompiler.o testCCompiler.c normal ppc c com.apple.compilers.gcc.4_0
    mkdir /Users/Malaterre/Dashboards/MyTests/CMake-Xcode2-gcc33/CMakeTmp/CMAKE_TRY_COMPILE.build/Debug/cmTryCompileExec.build/Objects-normal/ppc
    cd /Users/Malaterre/Dashboards/MyTests/CMake-Xcode2-gcc33/CMakeTmp
    /usr/bin/gcc-3.3 -x c -arch ppc -pipe -Wno-trigraphs -fpascal-strings -fasm-blocks -g -O0 -fmessage-length=0 -mtune=G4 -fvisibility=hidden -Wmost -Wno-four-char-constants -Wno-unknown-pragmas -mdynamic-no-pic -F/Users/Malaterre/Dashboards/MyTests/CMake-Xcode2-gcc33/CMakeTmp/Debug -I/Users/Malaterre/Dashboards/MyTests/CMake-Xcode2-gcc33/CMakeTmp/Debug/include -I/Users/Malaterre/Dashboards/MyTests/CMake-Xcode2-gcc33/CMakeTmp/CMAKE_TRY_COMPILE.build/Debug/cmTryCompileExec.build/DerivedSources -c /Users/Malaterre/Dashboards/MyTests/CMake-Xcode2-gcc33/CMakeTmp/testCCompiler.c -o /Users/Malaterre/Dashboards/MyTests/CMake-Xcode2-gcc33/CMakeTmp/CMAKE_TRY_COMPILE.build/Debug/cmTryCompileExec.build/Objects-normal/ppc/testCCompiler.o
cc1: error: unrecognized option `-fvisibility=hidden'


exporting CXXFLAGS='' did not help...

Thanks,
Mathieu