use VIPS_SONAME, if we can

see libvips/php-vips#27

Author: jcupitt

ChangeLog

@@ -1,6 +1,11 @@
 vips extension changelog
 
+dev
+---
+	* Use VIPS_SONAME, if we can
+
 Version 1.0.4 (2016-12-30)
+--------------------------
 	* Improve graceful fix from 1.0.3, see https://github.com/jcupitt/php-vips/issues/27
 	* Better notes section in package.xml, see https://github.com/jcupitt/php-vips/issues/28
 

vips.c

@@ -1646,7 +1646,12 @@ PHP_MINIT_FUNCTION(vips)
 		 * We can't just load .so, that's only installed with libvips-dev, 
 		 * which may not be present at runtime.
 		 */
-		if (!dlopen("libvips.so.42", RTLD_LAZY | RTLD_NODELETE)) {
+#ifdef VIPS_SONAME
+		if (!dlopen(VIPS_SONAME, RTLD_LAZY | RTLD_NODELETE)) 
+#else /*!VIPS_SONAME*/
+		if (!dlopen("libvips.so.42", RTLD_LAZY | RTLD_NODELETE)) 
+#endif /*VIPS_SONAME*/
+		{
 			sapi_module.sapi_error(E_WARNING, "php-vips-ext: unable to lock "
 				"libvips -- graceful may be unreliable");
 		}