try to fix make with -j

in all-hook, wait for libvips.la to appear

.travis.yml

@@ -5,7 +5,7 @@ before_script:
     --disable-dependency-tracking
     --with-jpeg-includes=$JPEG/include
     --with-jpeg-libraries=$JPEG/lib
-  - make -s V=0
+  - make -j$JOBS -s V=0
 script:
   - make -Ctest -j$JOBS -s V=0 VERBOSE=1 check
 

libvips/Makefile.am

@@ -65,7 +65,7 @@ EXTRA_DIST = \
 CLEANFILES = 
 
 all-local:
-	[ -f libvips.la ] && \
+	while [ ! -f libvips.la ]; do sleep 1; done; \ 
 	echo '/* This file is autogenerated, do not edit. */' > soname.h && \
 	source libvips.la && \
 	echo "#define VIPS_SONAME \"$$dlname\"" >> soname.h && \