[PATCH 2/3] configure: Fix building with SASL on Windows

[Philippe Mathieu-Daudé]

The Simple Authentication and Security Layer (SASL) library
re-defines the struct iovec on Win32 [*]. QEMU also re-defines
it in "qemu/osdep.h". The two definitions then clash on a MinGW
build.
We can avoid the SASL definition by defining STRUCT_IOVEC_DEFINED.
Add the definition to vnc_sasl_cflags if we are uing MinGW.

[*] 
https://github.com/cyrusimap/cyrus-sasl/blob/cyrus-sasl-2.1.27/include/sasl.h#L187

Cc: Alexey Pavlov <address@hidden>
Cc: Biswapriyo Nath <address@hidden>
Cc: Youry Metlitsky <address@hidden>
Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
---
 configure | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/configure b/configure
index 0c2dd1eb08..0bc87ce42a 100755
--- a/configure
+++ b/configure
@@ -3375,7 +3375,13 @@ if test "$vnc" = "yes" && test "$vnc_sasl" != "no" ; then
 int main(void) { sasl_server_init(NULL, "qemu"); return 0; }
 EOF
   # Assuming Cyrus-SASL installed in /usr prefix
-  vnc_sasl_cflags=""
+  if test "$mingw32" = "yes" && test "$iovec" != "yes"; then
+    # QEMU defines struct iovec in "qemu/osdep.h",
+    # we don't want libsasl to redefine it in <sasl/sasl.h>.
+    vnc_sasl_cflags="-DSTRUCT_IOVEC_DEFINED"
+  else
+    vnc_sasl_cflags=""
+  fi
   vnc_sasl_libs="-lsasl2"
   if compile_prog "$vnc_sasl_cflags" "$vnc_sasl_libs" ; then
     vnc_sasl=yes
-- 
2.21.1