Fix tests when using a separate build dir. (#2405)

configure.ac

@@ -1495,11 +1495,6 @@ AC_SUBST(VIPS_CONFIG)
 AC_SUBST(PACKAGES_USED)
 AC_SUBST(EXTRA_LIBS_USED)
 
-# needed by test/variables.sh.in
-# :( what's a better way to do this, argh
-TOP_SRCDIR=$ac_pwd
-AC_SUBST(TOP_SRCDIR)
-
 AC_CONFIG_FILES([
         vips.pc
         vips-cpp.pc

fuzz/test_fuzz.sh

@@ -3,6 +3,8 @@
 #set -x
 set -e
 
+. ../test/variables.sh
+
 # Glib is built without -fno-omit-frame-pointer. We need
 # to disable the fast unwinder to get full stacktraces.
 export ASAN_OPTIONS="fast_unwind_on_malloc=0:allocator_may_return_null=1"
@@ -14,7 +16,7 @@ export VIPS_WARNING=0
 ret=0
 
 for fuzzer in *_fuzzer; do
-  for file in common_fuzzer_corpus/*; do
+  for file in $top_srcdir/fuzz/common_fuzzer_corpus/*; do
     if ! ./$fuzzer $file; then
       echo FAIL $fuzzer $file
       ret=1

test/variables.sh.in

@@ -1,13 +1,14 @@
-top_srcdir=@TOP_SRCDIR@
+top_srcdir=@abs_top_srcdir@
+top_builddir=@abs_top_builddir@
 PYTHON=@PYTHON@
 # we need a different tmp for each script since make can run tests in parallel
 tmp=$top_srcdir/test/tmp-$$
 test_images=$top_srcdir/test/test-suite/images
 image=$test_images/sample.jpg
 mkdir -p $tmp
-vips=$top_srcdir/tools/vips
-vipsthumbnail=$top_srcdir/tools/vipsthumbnail
-vipsheader=$top_srcdir/tools/vipsheader
+vips=$top_builddir/tools/vips
+vipsthumbnail=$top_builddir/tools/vipsthumbnail
+vipsheader=$top_builddir/tools/vipsheader
 
 # we need bc to use '.' for a decimal separator
 export LC_NUMERIC=C