Replace "/usr/lib/mozilla" (the system-wide directory for extensions and
native manifests) with "$ICECAT_SYSTEM_DIR".

--- a/toolkit/xre/nsXREDirProvider.cpp
+++ b/toolkit/xre/nsXREDirProvider.cpp
@@ -293,24 +293,12 @@ nsresult nsXREDirProvider::GetBackgroundTasksProfilesRootDir(
 static nsresult GetSystemParentDirectory(nsIFile** aFile) {
   nsresult rv;
   nsCOMPtr<nsIFile> localDir;
-#  if defined(XP_MACOSX)
-  rv = GetOSXFolderType(kOnSystemDisk, kApplicationSupportFolderType,
-                        getter_AddRefs(localDir));
-  if (NS_SUCCEEDED(rv)) {
-    rv = localDir->AppendNative("Mozilla"_ns);
-  }
-#  else
-  constexpr auto dirname =
-#    ifdef HAVE_USR_LIB64_DIR
-      "/usr/lib64/mozilla"_ns
-#    elif defined(__OpenBSD__) || defined(__FreeBSD__)
-      "/usr/local/lib/mozilla"_ns
-#    else
-      "/usr/lib/mozilla"_ns
-#    endif
-      ;
-  rv = NS_NewNativeLocalFile(dirname, false, getter_AddRefs(localDir));
-#  endif
+
+  const char* systemParentDir = getenv("ICECAT_SYSTEM_DIR");
+  if (!systemParentDir || !*systemParentDir) return NS_ERROR_FAILURE;
+
+  rv = NS_NewNativeLocalFile(nsDependentCString(systemParentDir), false,
+                             getter_AddRefs(localDir));
 
   if (NS_SUCCEEDED(rv)) {
     localDir.forget(aFile);
'>tree</a><a href='/guix/commit/gnu/packages.scm?id=095516d897d73a6f5d82cfccf6c1135e876d313f'>commit</a><a href='/guix/diff/gnu/packages.scm?id=095516d897d73a6f5d82cfccf6c1135e876d313f'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages.scm'>
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<div class='path'>path: <a href='/guix/log/?id=095516d897d73a6f5d82cfccf6c1135e876d313f'>root</a>/<a href='/guix/log/gnu?id=095516d897d73a6f5d82cfccf6c1135e876d313f'>gnu</a>/<a href='/guix/log/gnu/packages.scm?id=095516d897d73a6f5d82cfccf6c1135e876d313f'>packages.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages.scm?id=095516d897d73a6f5d82cfccf6c1135e876d313f&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2024-12-01 20:14:15 +0100'>2024-12-01</span></td><td><a href='/guix/commit/gnu/packages.scm?id=4b5dae8defe4c0d5e98b5ce6abba853007485f23'>packages: Factorize ‘all-packages’.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages.scm (all-packages): New procedure.
* etc/source-manifest.scm (all-packages): Remove.
* guix/scripts/graph.scm (all-packages): Remove.
* guix/scripts/refresh.scm (all-packages): Remove.
* guix/scripts/weather.scm (all-packages): Remove.

Change-Id: I6072952c4b877b541037ce86402cfb7744eeb0a0
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-01-25 18:14:42 +0100'>2023-01-25</span></td><td><a href='/guix/commit/gnu/packages.scm?id=8b2721de6af76780611fe9f86fa5d4cd062400d1'>packages: Adjust 'generate-package-cache' for Guile 3.0.9.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages.scm (generate-package-cache): Adjust for Guile 3.0.9.
</span></span></td><td>Ludovic Courtès</td></tr>