This series of patches puts into the source files (in lib/ and build-aux/)
the license notices that match the module descriptions.

What to do with tiny files that, so far, have no copyright notice?
The Maintainers' Guide [1] allows to omit the copyright notice for "trivial"
files.
I find it reasonable to add a copyright and license notice to such tiny files
in Gnulib nevertheless, because:
  * It is debatable at which point a file starts to be "nontrivial".
  * The first line of a file should state its purpose. E.g. xstrtoull.c.
    Once it is done, the file is less trivial already.
  * Contributors to the file should know under which license they are
    contributing.
  * Packages which borrow files (as opposed to modules) from gnulib should
    not be surprised when a file with no license notice suddenly gets a
    license notice that they did not expect.
  * There are many tools for copyright and license checking [2] and we make
    their job easier by avoiding unclear situations regarding what is
    "nontrivial".
So, I added copyright and license notices to these files.

[1] https://www.gnu.org/prep/maintain/html_node/Copyright-Notices.html
[2] https://wiki.debian.org/CopyrightReviewTools


2021-06-04  Bruno Haible  <bruno@clisp.org>

	Put GPLv3+ notices in source files where appropriate.
	* lib/*.{h,c}: Use GPLv3+ notice whenever the module description says
	so.
	* build-aux/pmccabe.css: Likewise.

2021-06-04  Bruno Haible  <bruno@clisp.org>

	Put LGPLv3+ notices in source files where appropriate.
	* lib/*.{h,c}: Use LGPLv3+ notice whenever the module description says
	so.

2021-06-04  Bruno Haible  <bruno@clisp.org>

	Put "LGPLv3+ or GPLv2+" notices in source files where appropriate.
	* lib/**.{h,c,gperf}: Use "LGPLv3+ or GPLv2+" notice whenever the module
	description says so.

2021-06-04  Bruno Haible  <bruno@clisp.org>

	Generate correct license notices in libunistring files.
	* lib/gen-uni-tables.c (output_library_license, output_tests_license):
	New functions.
	(output_predicate, output_category, output_combclass,
	output_bidi_category, output_decimal_digit, output_digit,
	output_numeric, output_mirror, output_joining_type,
	output_joining_group, output_scripts, output_scripts_byname,
	output_blocks, output_ident_category, output_lbrk_tables,
	output_wbrk_tables, output_gbp_table, output_decomposition_tables,
	output_composition_tables, output_simple_mapping, output_casing_rules):
	Invoke output_library_license.
	(output_predicate_test, output_decimal_digit_test, output_digit_test,
	output_numeric_test, output_joining_type_test,
	output_joining_group_test, output_gbp_test, output_simple_mapping_test):
	Invoke output_tests_license.
	* lib/uni*/*.h, lib/uni*/*.gperf: Regenerated.
	* tests/uni*/*.h: Likewise.

2021-06-04  Bruno Haible  <bruno@clisp.org>

	Generate correct license notices in libunistring files.
	* lib/uniname/gen-uninames.lisp (main): Emit a copyright and license
	notice.
	* lib/uniname/uninames.h: Regenerated.

2021-06-04  Bruno Haible  <bruno@clisp.org>

	Put LGPLv2+ notices in source files where appropriate.
	* lib/**.{h,c,gperf}: Use LGPLv2+ notice whenever the module description
	says so.

2021-06-04  Bruno Haible  <bruno@clisp.org>

	Put "unlimited" notices in source files where appropriate.
	* build-aux/prefix-gnulib-mk: Use "unlimited" notice, since the module
	description says so.

2021-06-04  Bruno Haible  <bruno@clisp.org>

	Put public domain notices in source files where appropriate.
	* lib/{alloca.c,atexit.c,memmove.c}: Use public domain notice.