Make help

Dear Developers,
I'm trying to build LibreOffice, downloaded whit Git. I'm a trainee in
Hugary. I get this error with make:
...
[build CXX] UnpackedTarball/graphite/src/TtfUtil.cxx
[build CXX] UnpackedTarball/graphite/src/UtfCodec.cxx
[build LNK] StaticLibrary/libcodemaker_java.a
[build JCS] Jar/unoloader
[build C  ] bean/native/unix/com_sun_star_comp_beans_LocalOfficeWindow.c
[build C  ] bean/native/unix/com_sun_star_beans_LocalOfficeWindow.c
[build PAT] beanshell
javac: error: unrecognized command line option ‘-source’
javac: error: 1.5: No such file or directory
javac: error: unrecognized command line option ‘-target’
javac: error: 1.5: No such file or directory
make[1]: *** [/home/stalker08/git/libo/workdir/
unxlngi6.pro/JavaClassSet/Jar/unoloader/done] Error 1
make[1]: *** Waiting for unfinished jobs....

-----------------------------------------------------------------------
        Oh dear - something failed during the build - sorry !
  For more help with debugging build errors, please see the section in:
            http://wiki.documentfoundation.org/Development

  internal build errors:

ERROR: error 512 occurred while making
/home/stalker08/git/libo/tail_build/prj

 it seems that the error is inside 'tail_build', please re-run build
 inside this module to isolate the error and/or test your fix.

-----------------------------------------------------------------------
To rebuild a specific module:

make tail_build.clean # not recommended, this will re-build almost
everything
make tail_build

when the problem is isolated and fixed, re-run 'make'
make: *** [build-postprocess] Error 1
stalker08@linux-1u9f:~/git/libo> make tail_build

And then the following:
stalker08@linux-1u9f:~/git/libo> make tail_build
cd tail_build && make -j 6 -rs
[build LNK] Executable/bestreversemap
[build LNK] Library/libsal_textenc.so
[build JCS] Jar/unoloader
[build LNK] Library/libofficebean.so
javac: error: unrecognized command line option ‘-source’
javac: error: 1.5: No such file or directory
javac: error: unrecognized command line option ‘-target’
javac: error: 1.5: No such file or directory
make[1]: *** [/home/stalker08/git/libo/workdir/
unxlngi6.pro/JavaClassSet/Jar/unoloader/done] Error 1
make: *** [tail_build] Error 2
stalker08@linux-1u9f:~/git/libo>

My system is:
stalker08@linux-1u9f:~/git/libo> uname -a
Linux linux-1u9f.site 3.4.6-2.10-desktop #1 SMP PREEMPT Thu Jul 26 09:36:26
UTC 2012 (641c197) i686 i686 i386 GNU/Linux
OpenSUSE 11.2 running in VirtualBox on a Win7 host.

What should I do?
G.