How to fix linker error "cannot find crt1.o"?

I have a virtual Debian system which I use to develop. Today I wanted to try llvm/clang. After installing clang I can't compile my old c-projects (with gcc).

This is the error:

/usr/bin/ld: cannot find crt1.o: No such file or directory/usr/bin/ld: cannot find crti.o: No such file or directorycollect2: ld returned 1 exit status

I uninstalled clang and it still did not work. Does anyone have any idea how I can fix this?