try to fix soname.h again

now make in install-exec-hook so we are certain libvips.la has been built

TODO

@@ -1,7 +1,3 @@
-- vipsdisp-tiny makes stripes if the image is not tagged correctly
-
-  is one of the colourspace functions not reading format?
-
 - not sure about utf8 error messages on win
 
 - strange: 

libvips/Makefile.am

@@ -64,13 +64,11 @@ EXTRA_DIST = \
 
 CLEANFILES = 
 
-all-local:
-	while [ ! -f libvips.la ]; do sleep 1; done; sleep 1; \ 
+install-exec-hook:
 	echo '/* This file is autogenerated, do not edit. */' > soname.h && \
 	source libvips.la && \
 	echo "#define VIPS_SONAME \"$$dlname\"" >> soname.h && \
-	( cmp -s soname.h include/vips/soname.h || \
-		cp soname.h include/vips ) && \
+	cp soname.h $(DESTDIR)$(pkgincludedir) && \
 	rm soname.h
 
 -include $(INTROSPECTION_MAKEFILE)