lua: fix undeclared lua_writestringerror

[ligurio]

+ /src/aflplusplus/afl-clang-fast -O1 -fno-omit-frame-pointer -gline-tables-only -Wno-error=enum-constexpr-conversion -Wno-error=incompatible-function-pointer-types -Wno-error=int-conversion -Wno-error=deprecated-declarations -Wno-error=implicit-function-declaration -Wno-error=implicit-int -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address -fsanitize-address-use-after-scope -I/src/testdir/build/lua-master/source/ -c /src/fuzz_lua.c -o fuzz_lua.o [1m/src/fuzz_lua.c:79:14: [0m[0;1;35mwarning: [0m[1mcall to undeclared function 'lua_writestringerror'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration][0m
   79 |   if (pname) lua_writestringerror("%s: ", pname);[0m
      | [0;1;32m             ^
[0m1 warning generated.

[ligurio]

@DavidKorczynski could you please review? Initially, fuzz_lua.c was authored by you.

[github-actions]

ligurio is either the primary contact or is in the CCs list of projects/lua.
ligurio has previously contributed to projects/lua. The previous PR was #11804