imake: do not skip Linux* vendor definitions

Initial build failure is onserved on `staging` branch:

```
$ nix-build -A transfig
...
make[1]: Entering directory '/build/transfig.3.2.4'
Imakefile.c:20:2: Include file Imake.tmpl not found
imake: Exit code 1.
  Stop.
```

This happened after 8675ca0 ("xorg.xorgcffiles: 1.0.6 -> 1.0.7")
bump which exposed an old bug in `imake.patch`. `imake.patch`
dropped by accident definiton of `LinuxRedHat` enum and changed
evaluation of the following code:

```
 #if LinuxDistribution == LinuxRedHat
 ...
 # define ProjectRoot /usr
 #endif
```

References to `/usr` were addded in https://gitlab.freedesktop.org/xorg/util/cf/-/commit/d47131ed97ee491bb883c29ec0b106e8d5acfcd3.

Before this change `LinuxDistribution == LinuxRedHat` evaluated to true.
After this change `LinuxDistribution == LinuxRedHat` evaluates to false.

Mechanically I moved `#if 0` right after enum definitions but still
before system autodetection.

Now `transfig` builds successfully.

Closes: https://github.com/NixOS/nixpkgs/issues/135337
Signed-off-by: Sergei Trofimovich <slyich@gmail.com>

0 files changed, 0 insertions, 0 deletions