Updating and building blende [Fedora Linux]

Hello, I’ve successfully build blender a few months ago, but I cannot manage to update it and rebuild it.
I’m running Fedora 20 64bits.

When I try to rebuild, it fails. More specifically, I cannot link the final executable, because a bunch of function in the Imf_2_1 namespace fails to load :

/opt/lib/oiio/lib/libOpenImageIO.so: undefined reference to `Imf_2_1::Header::end() const'
/opt/lib/oiio/lib/libOpenImageIO.so: undefined reference to `Imf_2_1::IStream::readMemoryMapped(int)'
/opt/lib/oiio/lib/libOpenImageIO.so: undefined reference to `Imf_2_1::Attribute::Attribute()'

Also it warns me of a conflict between two versions of libHalf (which I don’t know what it is).

/usr/bin/ld: warning: libHalf.so.11, needed by /opt/lib/oiio/lib/libOpenImageIO.so, may conflict with libHalf.so.6

All I can say of this lib is that it is part of a package named ilmbase, which is up-to-date…

Also when trying to run ./build_files/build_environment/install_deps.sh again, the script tries to build OpenShadingLanguage-1.5.0 (other features are up-to-date), but it fails for an obscure reason…

[ 75%] Building CXX object src/liboslexec/CMakeFiles/oslexec.dir/llvm_ops.bc.cpp.o
Linking CXX shared library liboslexec.so
[ 75%] Built target oslexec
make: *** [all] Error 2
ERROR! OpenShadingLanguage-1.5.0 failed to compile, exiting

What’s wrong with my building steps ? Can you help me ?
Thank you !