When running tests in guile, look for *.scm files in ${DESTDIR}, so we
do not get a spurious error about running the installed versions.

Adjust the check for legit files to load to allow files out of
${DESTDIR} in addition to the build directory.

--- gnucash-5.11/common/cmake_modules/GncAddTest.cmake.~1~	Mon Nov 11 18:02:44 2024
+++ gnucash-5.11/common/cmake_modules/GncAddTest.cmake	Thu May  1 16:22:01 2025
@@ -34,6 +34,8 @@
   set(guile_load_paths "")
   list(APPEND guile_load_paths "${CMAKE_BINARY_DIR}/${GUILE_REL_SITEDIR}")
   list(APPEND guile_load_paths "${CMAKE_BINARY_DIR}/${GUILE_REL_SITEDIR}/gnucash/deprecated") # Path to gnucash' deprecated modules
+  list(APPEND guile_load_paths "$ENV{DESTDIR}/${CMAKE_INSTALL_PREFIX}/${GUILE_REL_SITEDIR}")
+  list(APPEND guile_load_paths "$ENV{DESTDIR}/${CMAKE_INSTALL_PREFIX}/${GUILE_REL_SITEDIR}/gnucash/deprecated")
   if (GUILE_COVERAGE)
     list(APPEND guile_load_paths "${CMAKE_BINARY_DIR}/${GUILE_REL_SITEDIR}/gnucash")
     list(APPEND guile_load_paths "${CMAKE_BINARY_DIR}/${GUILE_REL_SITEDIR}/gnucash/report")
@@ -119,6 +121,7 @@
           (lambda (filename)
               (when (and filename
                          (string-contains filename \"${GUILE_REL_SITEDIR}\")
+                         (not (string-prefix? \"$ENV{DESTDIR}\" filename))
                          (not (string-prefix? \"${CMAKE_BINARY_DIR}\" filename)))
                   (format #t \"%load-path = ~s~%\" %load-path)
                   (format #t \"%load-compiled-path = ~s~%\" %load-compiled-path)
@@ -144,6 +147,7 @@
           (lambda (filename)
               (when (and filename
                          (string-contains filename \"${GUILE_REL_SITEDIR}\")
+                         (not (string-prefix? \"$ENV{DESTDIR}\" filename))
                          (not (string-prefix? \"${CMAKE_BINARY_DIR}\" filename)))
                   (format #t \"%load-path = ~s~%\" %load-path)
                   (format #t \"%load-compiled-path = ~s~%\" %load-compiled-path)