Fix regression in how "pkg-config --static" output is handled

Change a1ea49878927dfe2 did replace different pkg-config calls for
-L, -l arguments to one. Anyhow, it also removed the eval() call that
ensured that the return string was split by whitespace, meaning that
paths couldn't resolve anymore properly if multiple arguments were
returned.

Fixes: QTBUG-79668
Change-Id: I4091fea6891ef79836e05f8e87ffa9d69863a8f5
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
(cherry picked from commit 99e43db7cea1c838993c151d2d40fc2874a94256)

mkspecs/features/qt_configure.prf

@@ -822,6 +822,8 @@ defineTest(qtConfLibrary_pkgConfig) {
         return(false)
     contains($${1}.libs, ".*\\.$${QMAKE_EXTENSION_STATICLIB}$") {
         qtRunLoggedCommand("$$pkg_config --static --libs $$args", libs)|return(false)
+        # Split by space
+        eval(libs = $$libs)
         !qtConfResolveLibs($${1}.libs, $$libs): \
             return(false)
     }