[tldistro] tl23 build fails at bibtex-x on Slackware 15.0

[texlive at schoepfer.info]

Hi,

it builds until enering bibtex-x:

Making all in bibtex-x
make[2]: Entering directory 
'/tmp/texlive-20230311-source/build/texk/bibtex-x'
make  all-am
make[3]: Entering directory 
'/tmp/texlive-20230311-source/build/texk/bibtex-x'
/bin/sh ./libtool  --tag=CC   --mode=link gcc -Wimplicit -Wreturn-type 
-O2 -fPIC   -o bibtex8 bibtex8-bibtex-1.o bibtex8-bibtex-2.o 
bibtex8-bibtex-3.o bibtex8-bibtex-4.o bibtex8-bibtex.o bibtex8-utils.o 
/tmp/texlive-20230311-source/build/texk/kpathsea/libkpathsea.la -lm
libtool: link: gcc -Wimplicit -Wreturn-type -O2 -fPIC -o .libs/bibtex8 
bibtex8-bibtex-1.o bibtex8-bibtex-2.o bibtex8-bibtex-3.o 
bibtex8-bibtex-4.o bibtex8-bibtex.o bibtex8-utils.o  
/tmp/texlive-20230311-source/build/texk/kpathsea/.libs/libkpathsea.so 
-lm
gcc -DHAVE_CONFIG_H -I. -I../../../texk/bibtex-x  
-I/tmp/texlive-20230311-source/build/texk 
-I/tmp/texlive-20230311-source/texk -DUNIX -DKPATHSEA -I/usr/include  
-DUTF_8  -Wimplicit -Wreturn-type -O2 -fPIC -MT bibtexu-bibtex-1.o -MD 
-MP -MF .deps/bibtexu-bibtex-1.Tpo -c -o bibtexu-bibtex-1.o `test -f 
'bibtex-1.c' || echo '../../../texk/bibtex-x/'`bibtex-1.c
../../../texk/bibtex-x/bibtex-1.c: In function ‘add_out_pool’:
../../../texk/bibtex-x/bibtex-1.c:333:18: error: 
‘UBLOCK_LATIN_EXTENDED_F’ undeclared (first use in this function); did 
you mean ‘UBLOCK_LATIN_EXTENDED_E’?
   333 |             case UBLOCK_LATIN_EXTENDED_F:
       |                  ^~~~~~~~~~~~~~~~~~~~~~~
       |                  UBLOCK_LATIN_EXTENDED_E
../../../texk/bibtex-x/bibtex-1.c:333:18: note: each undeclared 
identifier is reported only once for each function it appears in
../../../texk/bibtex-x/bibtex-1.c:334:18: error: 
‘UBLOCK_LATIN_EXTENDED_G’ undeclared (first use in this function); did 
you mean ‘UBLOCK_LATIN_EXTENDED_E’?
   334 |             case UBLOCK_LATIN_EXTENDED_G:
       |                  ^~~~~~~~~~~~~~~~~~~~~~~
       |                  UBLOCK_LATIN_EXTENDED_E
make[3]: *** [Makefile:977: bibtexu-bibtex-1.o] Error 1
make[3]: Leaving directory 
'/tmp/texlive-20230311-source/build/texk/bibtex-x'
make[2]: *** [Makefile:732: all] Error 2
make[2]: Leaving directory 
'/tmp/texlive-20230311-source/build/texk/bibtex-x'
make[1]: *** [Makefile:478: all-recursive] Error 1
make[1]: Leaving directory '/tmp/texlive-20230311-source/build/texk'
make: *** [Makefile:571: all-recursive] Error 1