Move src/dom/test/libtest test/libtest.sh, put path to it in TEST_LIB

Makefile.config.in

@@ -48,6 +48,9 @@ INSTALL_PROGRAM = @INSTALL_PROGRAM@ $(AM_INSTALL_PROGRAM_FLAGS)
 INSTALL_DATA = @INSTALL_DATA@
 INSTALL_SCRIPT = @INSTALL_SCRIPT@
 
+TEST_LIB=$(top_srcdir)/test/libtest.sh
+export TEST_LIB
+
 host = @host@
 
 ASCIIDOC = @ASCIIDOC@

src/dom/test/test-sgml-parser-basic

@@ -9,7 +9,7 @@ This test runs very basic features, like checking that nodes are placed
 correctly in the DOM tree.
 '
 
-. ./libtest
+. "$TEST_LIB"
 
 test_output_equals () {
 	desc="$1"; shift