Add #defines needed by OpenSolaris, fix breakage by the #defines

We need to define _XOPEN_SOURCE and __EXTENSIONS__ macros in order to get
CMSG_ and TIOCWIN macros defined. But then _POSIX_C_SOURCE gets defined, which
is (incorrectly) used as an indicator for existence of posix_memalign() in osdep.c.
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

configure

@@ -326,6 +326,10 @@ SunOS)
     audio_drv_list="oss"
   fi
   audio_possible_drivers="oss sdl"
+# needed for CMSG_ macros in sys/socket.h
+  QEMU_CFLAGS="-D_XOPEN_SOURCE=600 $QEMU_CFLAGS"
+# needed for TIOCWIN* defines in termios.h
+  QEMU_CFLAGS="-D__EXTENSIONS__ $QEMU_CFLAGS"
   QEMU_CFLAGS="-std=gnu99 $QEMU_CFLAGS"
   LIBS="-lsocket -lnsl -lresolv $LIBS"
 ;;

osdep.c

@@ -48,7 +48,7 @@
 #include "sysemu.h"
 #include "qemu_socket.h"
 
-#if !defined(_POSIX_C_SOURCE) || defined(_WIN32)
+#if !defined(_POSIX_C_SOURCE) || defined(_WIN32) || defined(__sun__)
 static void *oom_check(void *ptr)
 {
     if (ptr == NULL) {
@@ -87,7 +87,7 @@ void qemu_vfree(void *ptr)
 
 void *qemu_memalign(size_t alignment, size_t size)
 {
-#if defined(_POSIX_C_SOURCE)
+#if defined(_POSIX_C_SOURCE) && !defined(__sun__)
     int ret;
     void *ptr;
     ret = posix_memalign(&ptr, alignment, size);