Error with gnulib and i686 with older kernels

[Satadru Pramanik]

I am building gnulib via a 3rd party project (pax-utils) on a i686
system with 3.8 kernel headers.

I get this error. This is a recent regression causing the following
build failure. Any idea where I should start to look to get this
fixed?

make[3]: Entering directory
'/usr/local/tmp/crew/pax_utils.20220429204445.dir/pax-utils-1.3.4/autotools/gnulib'
make[4]: Entering directory
'/usr/local/tmp/crew/pax_utils.20220429204445.dir/pax-utils-1.3.4/autotools/gnulib'
  CC       libgnu_a-openat-proc.o
  CC       libgnu_a-chdir-long.o
  CC       libgnu_a-basename-lgpl.o
  CC       libgnu_a-cloexec.o
In file included from /usr/local/include/string.h:630,
                 from ./string.h:41,
                 from basename-lgpl.c:25:
./string.h:1091:1: error: expected identifier or ‘(’ before ‘__extension__’
 1091 | _GL_FUNCDECL_SYS (strndup, char *,
      | ^~~~~~~~~~~~~~~~
make[4]: *** [Makefile:2381: libgnu_a-basename-lgpl.o] Error 1
make[4]: *** Waiting for unfinished jobs....
In file included from /usr/local/include/string.h:630,
                 from ./string.h:41,
                 from openat-proc.c:30:
./string.h:1091:1: error: expected identifier or ‘(’ before ‘__extension__’
 1091 | _GL_FUNCDECL_SYS (strndup, char *,
      | ^~~~~~~~~~~~~~~~
make[4]: *** [Makefile:2367: libgnu_a-openat-proc.o] Error 1
In file included from /usr/local/include/string.h:630,
                 from ./string.h:41,
                 from chdir-long.c:27:
./string.h:1091:1: error: expected identifier or ‘(’ before ‘__extension__’
 1091 | _GL_FUNCDECL_SYS (strndup, char *,
      | ^~~~~~~~~~~~~~~~
make[4]: *** [Makefile:2409: libgnu_a-chdir-long.o] Error 1
make[4]: Leaving directory
'/usr/local/tmp/crew/pax_utils.20220429204445.dir/pax-utils-1.3.4/autotools/gnulib'
make[3]: *** [Makefile:4017: all-recursive] Error 1
make[3]: Leaving directory
'/usr/local/tmp/crew/pax_utils.20220429204445.dir/pax-utils-1.3.4/autotools/gnulib'
make[2]: *** [Makefile:2143: all] Error 2
make[2]: Leaving directory
'/usr/local/tmp/crew/pax_utils.20220429204445.dir/pax-utils-1.3.4/autotools/gnulib'
make[1]: *** [Makefile:2051: all-recursive] Error 1
make[1]: Leaving directory
'/usr/local/tmp/crew/pax_utils.20220429204445.dir/pax-utils-1.3.4'
make: *** [Makefile:1781: all] Error 2