Changes dictated by C23 standards

[mxmanghi]

Change declarations that break C23 standards. I took the liberty of renaming configure.in as configure.ac (as now customary with autotools) and also removed an unused directory from CFLAGS include arguments. Now the source code relies on config.h to define the PACKAGE_VERSION symbol

[resuna]

Tests failing here:

🍺  /opt/homebrew/Cellar/yajl/2.1.0: 19 files, 260.4KB
ln: /usr/local/include/tcl8.6: No such file or directory
Error: Process completed with exit code 1.

[gahr]

Tests failing here:

🍺  /opt/homebrew/Cellar/yajl/2.1.0: 19 files, 260.4KB
ln: /usr/local/include/tcl8.6: No such file or directory
Error: Process completed with exit code 1.

Please rebase, this should be fixed by #44.

[mxmanghi]

As per Jeff's suggestion CONST keywords were turned into standard const. I also defined MODULE_SCOPE in configure.ac in order to avoid a conflicting definition in Tcl9 but a clearly suboptimal solution

[bovine]

The Mac CI seems to be failing to find a yajl include:

In file included from ./generic/yajltcl.c:6:
./generic/yajltcl.h:14:10: fatal error: 'yajl/yajl_version.h' file not found
#include <yajl/yajl_version.h>

[mxmanghi]

The package doesn't build on Debian/Ubuntu and they are close to the pre-release freeze. If you want to take your time before integrating this pull request in a new bugfix release let me know. In that case I will produce a patch for the Debian package that fixes the C23 standards issue

[gahr]

This is the cause of the failure to build on mac. See the comment just above of this line. Why are you removing the fix?

[mxmanghi]

Even though the compilation flawlessly works on linux the options come with an -I /.. because YAJL_CFLAGS is an empty string. I guess the answer lies in a proper way to address the ticket quoted in the comments...the current status of the fix may be harmless for Linux but if we manage to have consistent option argument values it's safer (why tinkering with a non existing and incongruous '/..' directory after all?). Maybe we should let 'configure' build the YAJL_CFLAGS consistently with all the switches

-- M

[gahr]

How do you end up with an empty YAJL_CFLAGS, given this?

yajl-tcl/configure.in

Lines 191 to 192 in b737336

	PKG_CHECK_MODULES([YAJL], [yajl >= 2.0], [],
	[AC_MSG_ERROR([Cannot find yajl])])

[gahr]

I'm fine with fixing the pkg-config output earlier in configure. Can you please put the fix back until we do so?

[mxmanghi]

Done. It's part of this conversation now

[bovine]

The CI is still failing on Mac. Do we want to fix those before merging this?