Look for translatable strings in lib directory as well

The Character Encoding menu imported from goffice comes with many such strings.
I still need to find a nice way to copy the existing translations for them
from goffice directly to gnucash.

make-gnucash-potfiles.in

@@ -46,7 +46,7 @@ sub sort_func
 }
 
 my @possible_files = sort sort_func
-                      `cd @-SRCDIR-@ && find src -name '*.c' \\
+                      `cd @-SRCDIR-@ && find src lib -name '*.c' \\
                       -o -name '*.cpp' -o -name '*.glade' \\
                       -o -name '*.desktop.in' -o -name '*.keys.in' \\
                       -o -name '*.gschema.xml.in.in' -o -name '*.scm'`;

po/POTFILES.in

@@ -1,5 +1,12 @@
 # This is a list of files which contain translatable strings.
 # This file was generated by ../make-gnucash-potfiles.
+lib/goffice/go-charmap-sel.c
+lib/goffice/go-glib-extras.c
+lib/goffice/go-optionmenu.c
+lib/libc/libc-missing-noop.c
+lib/libc/setenv.c
+lib/libc/strfmon.c
+lib/libc/strptime.c
 src/app-utils/app-utils.scm
 src/app-utils/business-helpers.c
 src/app-utils/business-options.c