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
@@ -96,9 +96,9 @@
     "libKF5Parts.5.dylib",
     "libKF5Plasma.5.dylib"
 #else
-    "libKF5KIOCore.so.5",
-    "libKF5Parts.so.5",
-    "libKF5Plasma.so.5"
+    "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)
@@ -1673,7 +1673,7 @@
 #if defined(Q_OS_UNIX) && !defined(Q_OS_OSX)
     if (!d.suicide && qEnvironmentVariableIsEmpty("KDE_IS_PRELINKED")) {
         for (const char *extra_lib : extra_libs) {
-            const QString extra = findSharedLib(QString::fromLatin1(extra_lib));
+            const QString extra = QString::fromLatin1(extra_lib);
             if (!extra.isEmpty()) {
                 QLibrary l(extra);
                 l.setLoadHints(QLibrary::ExportExternalSymbolsHint);
ass='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=c96bb2e3dc826dd37f6ac29966831446bd59e964'>root</a>/<a href='/guix/log/build-aux?id=c96bb2e3dc826dd37f6ac29966831446bd59e964'>build-aux</a>/<a href='/guix/log/build-aux/cuirass?id=c96bb2e3dc826dd37f6ac29966831446bd59e964'>cuirass</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/cuirass?id=c96bb2e3dc826dd37f6ac29966831446bd59e964&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2018-04-08 17:48:33 +0200'>2018-04-08</span></td><td><a href='/guix/commit/build-aux/cuirass?id=351f384e57939005b25fa976952e3a0e08785893'>cuirass: Add job specs for the modular Guix.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-04-08 17:48:33 +0200'>2018-04-08</span></td><td><a href='/guix/commit/build-aux/cuirass?id=a1ec7540be9b30593f5e83e36a0e83b1bcf337f1'>cuirass: Factorize hydra-to-cuirass CI job translation.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-01-15 15:18:03 +0100'>2018-01-15</span></td><td><a href='/guix/commit/build-aux/cuirass?id=403f2dccfcf992573ceeeae7c76c71b4884d3cd4'>cuirass: Properly convert list of &lt;license&gt; objects.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-09-27 22:19:28 +0200'>2017-09-27</span></td><td><a href='/guix/commit/build-aux/cuirass?id=66bc1d2aaf74fc7eb4ef9b3519c69bd37142ffb3'>cuirass: Add gnu-system build spec.</a><span class='msg-avail'>...</span></td><td>Jan Nieuwenhuizen</td></tr>