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`).