Revert eb1b1a41 to avoid the use of fPIC flag as it is a "contagious" build option.

To not face the build error "relocation R_X86_64_32 against .rodata.str1.8 can not be used when making a shared object; recompile with -fPIC" while building a shared library without fPIC flag, gcc is compiled with -enable-default-pie flag (which is a compilation option used for gcc binaries provided by Debian by example, see gcc -v).