libc: Purge unneeded cdefs.h

These sys/cdefs.h are not needed. Purge them. They are mostly left-over
from the $FreeBSD$ removal. A few in libc are still required for macros
that cdefs.h defines. Keep those.

Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D42385

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

strfmon_l: Use specified locale for number formatting

strfmon_l does not take fully into consideration the explicitly passed
locale to perform the formatting.

Parallel universe bug report: https://sourceware.org/bugzilla/show_bug.cgi?id=19633

Obtained from: Darwin
Reviewed by: kib
PR: 267410
Github PR: #620
MFC after: 1 week

strfmon_test: Add a test for strfmon_l

Attempt to test the correctness of strfmon_l(3).

Items marked with XXX represent an invalid output.

Obtained from: https://github.com/NetBSD/src/commit/e7eba0044fe6128291cbb7e5923c7cf7d87318cc

Reviewed by: kib
PR: 267410
Github PR: #620
MFC after: 1 week

strfmon_test: Reserve space for the null terminator

Otherwise strfmon(3) could overflow the buffer.

Here is mostly done for correctness and illustrative purposes, as there
is no chance it could actually happen.

Reviewed by: kib
PR: 267410
Github PR: #620
MFC after: 1 week

strfmon: Fix formatting of a second fixed-width value

There is a bug when formatting two consecutive values using fixed-widths
and the values need padding. This was because the value of pad_size
was zeroed only every other time.

Format Before After
[%8n] [%8n] [ $123.45] [ $123.45] [ $123.45] [ $123.45]

Reviewed by: kib
PR: 267282
Github PR: #619
MFC after: 1 week

strfmon: Fix an edge case when sep_by_space is 2

Fix an edge case by printing the required space when, the currency
symbol succeeds the value, a space separates the sign from the value and
the sign position precedes the quantity and the currency symbol.

In other words:

n_cs_precedes = 0
n_sep_by_space = 2
n_sign_posn = 1

From The Open Group's localeconv[1]:

> When {p,n,int_p,int_n}_sep_by_space is 2:
> If the currency symbol and sign string are adjacent, a space separates
> them; otherwise, a space separates the sign string from the value.

Format Before After
[%n] [-123.45¤] [- 123.45¤]

[1]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/localeconv.html

Obtained from: Darwin
Reviewed by: kib
PR: 267282
Github PR: #619
MFC after: 1 week

strfmon: Fix alignment when enclosed by parentheses

Take into consideration the possibility of quantities enclosed by
parentheses when aligning.

Matches the examples from The Open Group's:

Format Before After
%(#5n [$ 123.45] [ $ 123.45 ] Use an alternative pos/neg style
[($ 123.45)] [($ 123.45)]
[$ 3,456.78] [ $ 3,456.78 ]

%!(#5n [ 123.45] [ 123.45 ] Disable the currency symbol
[( 123.45)] [( 123.45)]
[ 3,456.78] [ 3,456.78 ]

https://pubs.opengroup.org/onlinepubs/9699919799/functions/strfmon.html

SD5-XSH-ERN-29 is applied, updating the examples for %(#5n and %!(#5n.

Obtained from: Darwin
Reviewed by: kib
PR: 267282
Github PR: #619
MFC after: 1 week

strfmon: Trim the SPACE from international currency symbol

The international currency symbol (int_curr_symbol) has a mandatory
SPACE character as the last character.

Trim this space after reading it, otherwise this extra space will always
be printed when displaying the int_curr_symbol.

Fixes the output when the international currency format is selected
(%i).

Locale Format Before After
en_US.UTF-8 [%i] [USD 123.45] [USD123.45]
fr_FR.UTF-8 [%i] [123,45 EUR ] [123,45 EUR]

Note that the en_US.UTF-8 locale states that no space should be printed
between the currency symbol and the value (sep_by_space = 0).

Reviewed by: kib
PR: 267282
Github PR: #619
MFC after: 1 week

strfmon: Avoid an out-of-bounds access

Avoid an out-of-bounds access when trying to set the space_char using an
international currency format (%i) and the C/POSIX locale.

The current code tries to read the SPACE from int_curr_symbol[3]:

currency_symbol = strdup(lc->int_curr_symbol);
space_char = *(currency_symbol+3);

But on C/POSIX locales, int_curr_symbol is empty.

Three implementations have been examined: NetBSD[1], Darwin[2], and
Illumos[3]. Only NetBSD has fixed it[4].

Darwin and NetBSD also trim the mandatory final SPACE character after
reading it.

Locale Format Darwin/NetBSD FreeBSD/Illumos
en_US.UTF-8 [%i] [USD123.45] [USD 123.45]
fr_FR.UTF-8 [%i] [123,45 EUR] [123,45 EUR ]

This commit only fixes the out-of-bounds access.

[1]: https://github.com/NetBSD/src/blob/trunk/lib/libc/stdlib/strfmon.c
[2]: https://opensource.apple.com/source/Libc/Libc-1439.141.1/stdlib/NetBSD/strfmon.c.auto.html
[3]: https://github.com/illumos/illumos-gate/blob/master/usr/src/lib/libc/port/locale/strfmon.c
[4]: https://github.com/NetBSD/src/commit/3d7b5d498aa9609f2bc9ece9c734c5f493a8e239

Reviewed by: kib
PR: 267282
Github PR: #619
MFC after: 1 week

strfmon_test: Add some tests

Attempt to test the correctness of strfmon(3).

Some of them were inspired from the examples section at:
https://pubs.opengroup.org/onlinepubs/9699919799/functions/strfmon.html

Items marked with XXX represent an invalid output.

Reviewed by: kib
PR: 267282
Github PR: #619
MFC after: 1 week

strfmon_test: Fix typo and remove extra space

Reviewed by: kib
PR: 267282
Github PR: #619
MFC after: 1 week

Allow multi-byte thousands separators in strfmon(3)

PR: 234010
Reported by: Jon Tejnung <jon AT herrskogen.se>
Reviewed by: yuripv
Differential Revision: https://reviews.freebsd.org/D18605