components/valgrind.bst: Disable stack protector in compile flags

Instead of recomposing compile flags in the bst file.
Status Job ID Name Coverage
  Flatpak
passed #231901089
aarch64
app_aarch64

16:12:08

passed #231915598
armhf
app_arm

05:00:54

passed #231901088
cache_i686 x86_64
app_i686

07:36:06

passed #231901087
cache_x86_64 x86_64
app_x86_64

08:17:10

failed #231901090
armhf
app_arm

01:27:40

 
  Vm
manual #231901093
aarch64 allowed to fail manual
minimal_systemd_vm_aarch64
passed #231901094
armhf
minimal_systemd_vm_arm

00:03:26

passed #231901092
cache_i686 x86_64
minimal_systemd_vm_i686

00:02:33

passed #231901091
cache_x86_64 x86_64
minimal_systemd_vm_x86_64

00:02:35