src: conditionalize use of O_DIRECT

The O_DIRECT flag is not available on all platforms, so we
must introduce a compat define the same way gnulib does.

Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

src/util/iohelper.c

@@ -39,6 +39,10 @@
 
 #define VIR_FROM_THIS VIR_FROM_STORAGE
 
+#ifndef O_DIRECT
+# define O_DIRECT 0
+#endif
+
 static int
 runIO(const char *path, int fd, int oflags)
 {

src/util/virfile.c

@@ -95,6 +95,10 @@
 
 VIR_LOG_INIT("util.file");
 
+#ifndef O_DIRECT
+# define O_DIRECT 0
+#endif
+
 int virFileClose(int *fdptr, virFileCloseFlags flags)
 {
     int saved_errno = 0;