libgettextpo: Remove static variable error_with_progname.
Inside libgettextpo, assignments to error_with_progname are undesired.
Outside libgettextpo, they are redundant.
* gettext-tools/src/read-po-lex.c: Don't include error-progname.h.
* gettext-tools/src/read-properties.c: Don't include error-progname.h.
(read_escaped_string): Remove assignments to error_with_progname.
* gettext-tools/src/read-stringtable.c: Don't include error-progname.h.
* gettext-tools/src/write-catalog.c: Don't include error-progname.h.
(msgdomain_list_print): Remove assignments to error_with_progname.
* autogen.sh (GNULIB_MODULES_LIBGETTEXTPO): Remove error-progname.
