Search the "extra libs" in GUIX_KF5INIT_LIB_PATH (which basically is a
collection of all /lib directories). We can not hard-code the full path to the
libsKF5Plasam, since adding palse-workspace

Adopted from NixOS
pkgs/development/libraries/kde-frameworks/kinit/kdeinit-extra_libs.patch

===================================================================
--- kinit-5.32.0/src/kdeinit/kinit-5.32.0/src/kdeinit/.orig
+++ kinit-5.32.0/src/kdeinit/kinit.cpp
@@ -96,11 +96,9 @@
     "libKF5Parts.5.dylib",
     "libKF5Plasma.5.dylib"
 #else
-    "libKF5KIOCore.so.5",
-    "libKF5Parts.so.5",
-//#ifdef __KDE_HAVE_GCC_VISIBILITY // Removed for KF5, we'll see.
-    "libKF5Plasma.so.5"
-//#endif
+    "GUIX_PKGS_KF5_KIO/lib/libKF5KIOCore.so.5",
+    "GUIX_PKGS_KF5_PARTS/lib/libKF5Parts.so.5",
+    "GUIX_PKGS_KF5_PLASMA/lib/libKF5Plasma.so.5"
 #endif
 };
 #endif
@@ -1533,20 +1531,6 @@ static int initXconnection()
 }
 #endif
 
-#ifndef Q_OS_OSX
-// Find a shared lib in the lib dir, e.g. libkio.so.
-// Completely unrelated to plugins.
-static QString findSharedLib(const QString &lib)
-{
-    QString path = QFile::decodeName(CMAKE_INSTALL_PREFIX "/" LIB_INSTALL_DIR "/") + lib;
-    if (QFile::exists(path)) {
-        return path;
-    }
-    // We could also look in LD_LIBRARY_PATH, but really, who installs the main libs in different prefixes?
-    return QString();
-}
-#endif
-
 extern "C" {
 
     static void secondary_child_handler(int)
@@ -1689,7 +1693,7 @@
     if (!d.suicide && qEnvironmentVariableIsEmpty("KDE_IS_PRELINKED")) {
         const int extrasCount = sizeof(extra_libs) / sizeof(extra_libs[0]);
         for (int i = 0; i < extrasCount; i++) {
-            const QString extra = findSharedLib(QString::fromLatin1(extra_libs[i]));
+            const QString extra = QString::fromLatin1(extra_libs[i]);
             if (!extra.isEmpty()) {
                 QLibrary l(extra);
                 l.setLoadHints(QLibrary::ExportExternalSymbolsHint);
ch'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=cf78318204aff1ed443094a3428dfeed859f0c8a'>root</a>/<a href='/guix/log/build-aux?id=cf78318204aff1ed443094a3428dfeed859f0c8a'>build-aux</a>/<a href='/guix/log/build-aux/test-env.in?id=cf78318204aff1ed443094a3428dfeed859f0c8a'>test-env.in</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/build-aux/test-env.in?id=cf78318204aff1ed443094a3428dfeed859f0c8a&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-12-22 10:53:19 +0100'>2021-12-22</span></td><td><a href='/guix/commit/build-aux/test-env.in?id=9ebc9ca070a21ba0aeb3f61202a8071bb250ccc8'>tests: Move keys into ./tests/keys/ and add a third ed25519 key.</a><span class='msg-avail'>...</span></td><td>Attila Lendvai</td></tr>
<tr><td><span title='2021-04-20 12:13:16 +0200'>2021-04-20</span></td><td><a href='/guix/commit/build-aux/test-env.in?id=d95168321f4a9bf6857b598da0a183b45a868d54'>import: Remove Nix importer.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>