Enable full RELRO on linux (#53528)
This enables full RELRO (Read-Only Relocations) on Linux.
It is helpful for hardening Linux binaries and prevents GOT overwrite
attacks.
There is some concern this would slow down startup or package load, but
under
the following workloads there is no detectable difference, and infact
RELRO
appears slightly faster.
```
time julia -e 'using Pkg; using LinearAlgebra; exit()'
time julia -e 'exit()'
```
Master sys time average: 0.052
This commit sys time average: 0.044
We can validate that "full RELRO" is enabled with checksec:
```
[nix-shell:~/src/julia]$ checksec --file=./julia
RELRO STACK CANARY NX PIE RPATH RUNPATH Symbols FORTIFY Fortified Fortifiable FILE
Full RELRO No canary found NX enabled No PIE No RPATH RUNPATH 39 Symbols No 0 0 ./julia
```
