clc: force fPIC for every user when using shared LLVM

As we want to start using `dladdr`, this is needed to prevent `dladdr`
returning information of the wrong file.

Fixes tag as it's required by the actual fix.

Signed-off-by: Karol Herbst <kherbst@redhat.com>
Fixes: e22491c832 ("clc: fetch clang resource dir at runtime")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25568>
(cherry picked from commit 8efd11fce9)

.pick_status.json

@@ -184,7 +184,7 @@
         "description": "clc: force fPIC for every user when using shared LLVM",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "e22491c83265200f518e9fb4deff54e3c2823b68",
         "notes": null

src/compiler/clc/meson.build

@@ -125,7 +125,13 @@ _libmesaclc = static_library(
                  idep_mesautil, dep_spirv_tools]
 )
 
+_idep_mesaclc_link_args = []
+if _shared_llvm
+  _idep_mesaclc_link_args += cc.get_supported_link_arguments('-fPIC')
+endif
+
 idep_mesaclc = declare_dependency(
   link_with : _libmesaclc,
   include_directories : include_directories('.'),
+  link_args : _idep_mesaclc_link_args,
 )