Hi janhendrik,
From your first message (see below), we can see you are using the wrong C library. You can use newlib when you build a standalone applicaiton, but if you want to build an application for uClinux, you have to use uClibc. The message shows that you are using newlib coming with the toolchain.
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cygdrive/c/altera/kits/nios2/bin/nios2-gnutools/H-i686-pc-cygwin/bin/../lib/gcc
-lib/nios2-elf/3.3.3/../../../../nios2-elf/lib/libc.a(closer.o): In function `_c
lose_r':[/b]
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