Add -fPIC to compilation flags
    
    Build was failing with:
    mpicc -o build/bin.linux-x86_64-2.7//gpaw-python build/temp.linux-x86_64-2.7/c/plane_wave.o build/temp.linux-x86_64-2.7/c/lcao.o build/temp.linux-x86_64-2.7/c/_gpaw.o build/temp.linux-x86_64-2.7/c/plt.o build/temp.linux-x86_64-2.7/c/transformers.o build/temp.linux-x86_64-2.7/c/point_charges.o build/temp.linux-x86_64-2.7/c/mlsqr.o build/temp.linux-x86_64-2.7/c/wigner_seitz.o build/temp.linux-x86_64-2.7/c/spline.o build/temp.linux-x86_64-2.7/c/localized_functions.o build/temp.linux-x86_64-2.7/c/blas.o build/temp.linux-x86_64-2.7/c/cerf.o build/temp.linux-x86_64-2.7/c/lfc.o build/temp.linux-x86_64-2.7/c/blacs.o build/temp.linux-x86_64-2.7/c/bc.o build/temp.linux-x86_64-2.7/c/utilities.o build/temp.linux-x86_64-2.7/c/lapack.o build/temp.linux-x86_64-2.7/c/fftw.o build/temp.linux-x86_64-2.7/c/lfc2.o build/temp.linux-x86_64-2.7/c/operators.o build/temp.linux-x86_64-2.7/c/hdf5.o build/temp.linux-x86_64-2.7/c/mpi.o build/temp.linux-x86_64-2.7/c/symmetry.o build/temp/usr/bin/ld: build/temp.linux-x86_64-2.7/c/_gpaw.o: relocation R_X86_64_32 against rodata' can not be used when making a shared object; recompile with -fPIC
    build/temp.linux-x86_64-2.7/c/_gpaw.o: error adding symbols: Bad value