Fix path replacement on install for header module prl files

For prefix builds the prl files of header modules still contained the
absolute path of the install prefix instead of $$[QT_INSTALL_LIBS]. This
was, because the QMAKE_PRL_INSTALL_REPLACE variable was only filled for
'lib' TEMPLATE projects. Header modules, however, have the 'aux'
template.

Fixes: QTBUG-82871
Change-Id: I90f248967f1bff41423d871a977ae91c78015bbd
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

mkspecs/features/qt_common.prf

@@ -26,7 +26,8 @@ contains(TEMPLATE, .*lib) {
     if(!host_build|!cross_compile):qtConfig(reduce_exports): CONFIG += hide_symbols
     unix:qtConfig(reduce_relocations): CONFIG += bsymbolic_functions
     qtConfig(separate_debug_info): CONFIG += separate_debug_info
-
+}
+contains(TEMPLATE, .*lib)|contains(TEMPLATE, aux) {
     !isEmpty(_QMAKE_SUPER_CACHE_): \
         rplbase = $$dirname(_QMAKE_SUPER_CACHE_)/[^/][^/]*
     else: \