Compile with -fPIC

When linking against my fcgi_app_core[1] project I got this linker error

    /usr/bin/ld: ../../libflate/libflate.a(flate.o): relocation
    R_X86_64_32 against `.rodata' can not be used when making a
    shared object; recompile with -fPIC
    ../../libflate/libflate.a: could not read symbols: Bad value

[1] - https://github.com/ac000/fcgi_app_core

Signed-off-by: Andrew Clayton <andrew@digital-domain.net>