[PATCH 0/1] MR4642: configure: Use Wine includes for cross compiler checks.

[Jacek Caban (＠jacek)]

C99 checks depend on stddef.h and stdarg.h. Those headers are usually shipped with
compilers (and another copy of them as part of mingw-w64 for targets that use it),
but some providers skip them. We use our own version during the build anyway, so
we may use them for configure checks as well.

[PATCH 1/1] configure: Use Wine includes for cross compiler checks.

[Jacek Caban]

From: Jacek Caban

C99 checks depend on stddef.h and stdarg.h. Those headers are usually shipped with
compilers (and another copy of them as part of mingw-w64 for targets that use it),
but some providers skip them. We use our own version during the build anyway, so
we may use them for configure checks as well.
---
 configure.ac | 1 +
 1 file changed, 1 insertion(+)

diff --git a/configure.ac b/configure.ac
index 26bcc3f6c21..0dc083bec86 100644
--- a/configure.ac
+++ b/configure.ac
@@ -924,6 +924,7 @@ This is an error since --enable-archs=$wine_arch was requested.])])
         continue
     fi

+    CFLAGS="$CFLAGS -I$srcdir/include/msvcrt/ -I$srcdir/include/"
     AS_VAR_PUSHDEF([wine_cv_crosscc_c99],[ac_cv_${wine_arch}_crosscc_c99])
     AC_MSG_CHECKING([for $CC option to enable C99 features])
     AC_CACHE_VAL([wine_cv_crosscc_c99],

[Brendan Shanks (＠bshanks)]

On FreeBSD, this enables LLVM from ports to be used as the mingw cross-compiler:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=274542

```
$ export PATH=/usr/local/llvm17/bin:$PATH
$ ./configure --enable-win64 --with-mingw=clang CC=clang CXX=clang++ CPPFLAGS=-I/usr/local/include
```

I filed [a bug report](https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=274542) for FreeBSD excluding these header files, and [am starting](https://github.com/freebsd/freebsd-src/pull/915) to fix it.