Small cross-compile fixes

- $GENICAM_GENTL64_PATH may be defined in Linux but the path inside the
dir is then invalid when cross-compiling for Windows
- rang.hpp included transitively from video_frame_pool.cpp needs _WIN32_WINNT
at least to _WIN32_WINNT_VISTA prior including other headers - it is
defined in config_win32.h

configure.ac

@@ -1120,7 +1120,7 @@ else
                 XI_LIB_PREF="lib"
                 XIMEA_CFLAGS="-I$XIAPI_PATH/../include"
         else
-                if test -n "$GENICAM_GENTL64_PATH"; then
+                if test -d "$GENICAM_GENTL64_PATH/../../API/xiAPI"; then
                         # the env var contains actually something like "C:\XIMEA\GenTL Producer\64bit"
                         XIAPI_PATH=$(realpath "$GENICAM_GENTL64_PATH/../../API/xiAPI")
                 else

src/utils/video_frame_pool.cpp

@@ -35,6 +35,12 @@
  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif // defined HAVE_CONFIG_H
+#include "config_unix.h"
+#include "config_win32.h"
+
 #include <cassert>
 #include <functional>
 #include <iostream>