NLS not detected: implicit declaration in ./configure

[dmacks]

Describe the bug
A fink user has reported that even when libintl and libiconv are available (via fink), neon's ./configure does not detect that i18n support is available. He's running OS X 10.15 (Xcode 12.4), which has -Werror-implicit-function-declaration by default. On older Xcode, it i18n is detected properly, but I can reproduce the non-detection by passing that -W via CFLAGS.

Environment

• neon version: 0.32.1
• OS: OS X 10.15

Debugging output
Compare config.log with that -Werror:

configure:17472: gcc -o conftest -Os -Werror-implicit-function-declaration  -MD -I/sw/include -no-cpp-precomp -I/sw/include -I/sw/include -I/sw/include/libxml2 -I/sw/include -Wl,-dead_strip_dylibs -L/sw/lib conftest.c  -lintl  -lz -L/sw/lib -lssl -lcrypto -dynamic -Wl,-search_paths_first -lkrb5 -L/sw/lib -lproxy -L/sw/lib -lxml2 >&5
conftest.c:120:1: error: implicit declaration of function 'bindtextdomain' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
bindtextdomain();
^
1 error generated.
configure:17472: $? = 1
[...]
configure:17502: result: not found

vs without:

configure:17472: gcc -o conftest -Os  -MD -I/sw/include -no-cpp-precomp -I/sw/include -I/sw/include -I/sw/include/libxml2 -I/sw/include -Wl,-dead_strip_dylibs -L/sw/lib conftest.c  -lintl  -lz -L/sw/lib -lssl -lcrypto -dynamic -Wl,-search_paths_first -lkrb5 -L/sw/lib -lproxy -L/sw/lib -lxml2 >&5
conftest.c:120:1: warning: implicit declaration of function 'bindtextdomain' is invalid in C99 [-Wimplicit-function-declaration]
bindtextdomain();
^
1 warning generated.
configure:17472: $? = 0
configure:17502: result: -lintl

This is another case like #45, and the same type of solution works: putting in neon.m4's NE_SEARCH_LIBS:

    bindtextdomain)
      ne__prologue="#include <libintl.h>"                                       
      ne__code="bindtextdomain(\"\",\"\");"
      ;;

[dmacks]

Fixed by https://github.com/fink/fink-distributions/blob/62f4b73d054a5bfd8eea22840cf6e4427856c204/10.9-libcxx/stable/main/finkinfo/libs/neon27.patch#L22-L34

[notroj]

Thanks for the patch, merged.