maint: remove empty lines at EOF, but excluding modules/*

maint: remove empty lines at EOF, but excluding modules/*

Apply syntax rules at home as well as abroad.  Most changes
were induced by running this:
  make srcdir=. _build-aux=build-aux -f top/maint.mk \
    sc_prohibit_empty_lines_at_EOF | grep -v modules/ \
    | xargs perl -pi -0777 -e 's/\n\n+$/\n/'
* cfg.mk (local-checks-to-skip): Enable sc_prohibit_empty_lines_at_EOF.
Exempt modules/* and two binary files.
Also exclude doc/INSTALL*, per request from Bruno Haible.
* doc/regexprops-generic.texi: *Add* a newline at EOF.  There was none.
* doc/Copyright/assign.translation.manual: Remove empty lines at EOF.
* doc/Copyright/request-assign.future: Likewise.
* doc/Copyright/request-disclaim.changes: Likewise.
* doc/INSTALL: Likewise.
* doc/INSTALL.ISO: Likewise.
* doc/INSTALL.UTF-8: Likewise.
* doc/acl-cygwin.txt: Likewise.
* doc/acl-resources.txt: Likewise.
* doc/fdl-1.2.texi: Likewise.
* doc/fdl-1.3.texi: Likewise.
* doc/fdl.texi: Likewise.
* lib/argp-pin.c: Likewise.
* lib/round.c: Likewise.
* lib/unicase/u16-totitle.c: Likewise.
* lib/unictype/block_test.c: Likewise.
* lib/uninorm/canonical-decomposition.c: Likewise.
* m4/README: Likewise.
* m4/relocatable-lib.m4: Likewise.
* tests/test-isnand-nolibm.c: Likewise.
* tests/test-isnand.c: Likewise.
* tests/uninorm/NormalizationTest.txt: Likewise.