test for orc 0.4.31

the version that should start working again, hopefully

configure.ac

@@ -778,6 +778,19 @@ if test x"$with_orc" != x"no"; then
   )
 fi
 
+# orc 0.4.30+ works with cf-protection, but 0.4.30 has a bug with multiple
+# definitions of OrcTargetPowerPCFlags, so insist on 0.4.31
+if test x"$with_orc" = x"yes"; then
+  PKG_CHECK_MODULES(ORC_CF_PROTECTION, orc-0.4 >= 0.4.31,
+    [AC_DEFINE(HAVE_ORC_CF_PROTECTION,1,
+	       [define if your orc works with cf-protection.]
+     )
+    ],
+    [:
+    ]
+  )
+fi
+
 # lcms ... refuse to use lcms1
 AC_ARG_WITH([lcms], 
   AS_HELP_STRING([--without-lcms], [build without lcms (default: test)]))

libvips/include/vips/vector.h

@@ -37,15 +37,17 @@
 /* If we are building with -fcf-protection (run-time checking of
  * indirect jumps) then Orc won't work. Make sure it's off.
  *
- * Orc may support -fcf-protection in the future, but does not in June 2019.
- *
  * https://gcc.gnu.org/onlinedocs/gcc/\
  * 	Instrumentation-Options.html#index-fcf-protection
  * https://gitlab.freedesktop.org/gstreamer/orc/issues/17
+ *
+ * orc 0.4.30 and later work with cf-protection.
  */
 #ifdef __CET__
+#ifndef HAVE_ORC_CF_PROTECTION
 #undef HAVE_ORC
 #endif
+#endif
 
 #ifdef HAVE_ORC
 #include <orc/orc.h>

libvips/iofuncs/vector.c

@@ -44,8 +44,8 @@
  */
 
 /*
-#define DEBUG
  */
+#define DEBUG
 
 /* Trace all orc calls, handy for debugging.
 #define DEBUG_TRACE
@@ -54,6 +54,7 @@
 #ifdef HAVE_CONFIG_H
 #include <config.h>
 #endif /*HAVE_CONFIG_H*/
+
 #include <vips/intl.h>
 
 #include <stdlib.h>
@@ -83,6 +84,10 @@ vips_vector_error( VipsVector *vector )
 void 
 vips_vector_init( void )
 {
+#ifdef HAVE_ORC
+	printf( "HAVE_ORC\n" );
+#endif /*HAVE_ORC*/
+
 #ifdef HAVE_ORC
 #ifdef DEBUG_TRACE
 	printf( "orc_init();\n" );