[test] Add cairo-test-trace

The basic premise is that we feed the trace to multiple backends in
parallel and compare the output at the end of each context (based on
the premise that contexts demarcate expose events, or their logical
equivalents) with that of the image[1] backend. Each backend is
executed in a separate process, for robustness, with the image data
residing in shared memory and synchronising over a socket.

[1] Should be reference implementation, currently the image backend is
    considered to be the reference for all other backends.

test/Makefile.am

@@ -95,6 +95,20 @@ if HAVE_PTHREAD
 cairo_test_suite_LDADD += -lpthread
 endif
 
+cairo_test_trace_SOURCES =		\
+	cairo-test-trace.c
+cairo_test_trace_LDADD =		\
+	$(top_builddir)/util/cairo-script/libcairo-script-interpreter.la \
+        $(top_builddir)/boilerplate/libcairoboilerplate.la	\
+	$(top_builddir)/src/libcairo.la 			\
+	$(CAIRO_LDADD) \
+	-lrt
+cairo_test_trace_DEPENDENCIES = \
+	$(top_builddir)/util/cairo-script/libcairo-script-interpreter.la \
+        $(top_builddir)/boilerplate/libcairoboilerplate.la	\
+	$(top_builddir)/src/libcairo.la
+EXTRA_DIST += dlmalloc.c
+
 BUILT_SOURCES += cairo-test-constructors.c
 noinst_SCRIPTS = make-cairo-test-constructors.pl
 EXTRA_DIST += $(BUILT_SOURCES) $(noinst_SCRIPTS) COPYING
@@ -1153,7 +1167,7 @@ $(top_builddir)/test/pdiff/libpdiff.la:
 $(top_builddir)/util/cairo-script/libcairo-script-interpreter.la: $(top_builddir)/src/libcairo.la
 	cd $(top_builddir)/util/cairo-script && $(MAKE) $(AM_MAKEFLAGS) libcairo-script-interpreter.la
 
-EXTRA_PROGRAMS += imagediff png-flatten
+EXTRA_PROGRAMS += imagediff png-flatten cairo-test-trace
 
 imagediff_SOURCES = \
 	imagediff.c	\