[Semi-regression] C code contains backtick`gensym

[mratsim]

As mentioned in Discord at https://discord.com/channels/371759389889003530/768367394547957761/1250440092208730152

Using the latest version2-0 branch I have a regression compared to 2.0.4 that leads to backtick of gensym'ed symbols not being translated to X60 as usual due to https://github.com/nim-lang/Nim/pull/22944 being backported.

See CI run: https://github.com/mratsim/constantine/actions/runs/9471919674/job/26096274691?pr=393#step:23:47

It seems to also lead to conflicting types using same name variables

https://github.com/mratsim/constantine/actions/runs/9471919674/job/26096274691?pr=393#step:23:13

---

Reproducing

git clone https://github.com/mratsim/constantine
cd constantine
nim c --cc:clang --outdir:build -d:danger --hints:off --warnings:off --verbosity:0 --threads:on --noMain --app:lib --nimMainPrefix:ctt_init_ --nimcache:nimcache/X60 bindings/lib_constantine.nim

Note that gcc-14 has issues that might not be backported yet so it's easier to use Clang (https://github.com/nim-lang/Nim/pulls?q=is%3Apr+%22gcc+14%22+is%3Aclosed+ )

---

Similar bug

If it helps, in the past I used to have those issues in v2.0.4, but only in templates and only with {.noInit.} variables.

I found 2 workarounds:

1. functions see: https://github.com/mratsim/constantine/pull/338/files#diff-9d369fc072ba230397943805ef3e09f4726cef5166ed8774d71657ee0fe0a6c1L1442

2. Using inject see: https://github.com/mratsim/constantine/pull/346/files#diff-9af16dfbdb13c0086d14ae9290dab7feba9d35fe1e14f3a4f8ca04455aef49b2L68

   Unfortunately I tried to minimize the issue to a single file and failed at the time.

[mratsim]

Also it's important to note that some errors are generated even in files with no push

https://github.com/mratsim/constantine/blob/master/constantine/math/extension_fields/square_root_fp2.nim

The z_NEQ variable comes from this template: https://github.com/mratsim/constantine/blob/6ca7cbf/constantine/platforms/constant_time/ct_routines.nim#L138-L141

and the top of the file pushes {.inline.}, which is not applied to templates, and {.raises: [].}