Fix firefox failing build (#217)

Hi,

After some experimentation and digging in the firefox repository I realized that the commas in _link-arg_ are the cause of the error.

Also, correct me if I'm wrong here, but you do not have to pass -Wl to the linker, cargo handles that. Plus, according to the [documentation](https://doc.rust-lang.org/rustc/codegen-options/index.html#link-arg), it is possible to pass _link-arg_ multiple times to achieve the same result.

I managed to build firefox locally with this change, so I guess this should work here as well.

Reviewed-on: #217
Co-authored-by: strptrk <git@patrikstier.com>
Co-committed-by: strptrk <git@patrikstier.com>

flags.yaml

@@ -20,7 +20,7 @@ common:
   packager: "ALHP $march$ <alhp@harting.dev>"
   makeflags: "-j$buildproc$"
   # https://somegit.dev/ALHP/ALHP.GO/issues/110
-  rustflags: "-Copt-level=3 -Ctarget-cpu=$march$ -Clink-arg=-Wl,-z,pack-relative-relocs"
+  rustflags: "-Copt-level=3 -Ctarget-cpu=$march$ -Clink-arg=-z -Clink-arg=pack-relative-relocs"
   ltoflags:
     - "-falign-functions=32" # https://github.com/InBetweenNames/gentooLTO/issues/164
   kcflags: " -march=$march$ -O3"