tests: Fix schema parser test for in-tree build

Commit 4f193e34 added the test, but screwed up in-tree builds
(SRCDIR=.): the tests's output overwrites the expected output, and is
thus compared to itself.

Cc: qemu-stable@nongnu.org
Reported-by: NLaszlo Ersek <lersek@redhat.com>
Reviewed-by: NAndreas Färber <afaerber@suse.de>
Reviewed-by: NLaszlo Ersek <lersek@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>
(cherry picked from commit d8039e58)
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

tests/.gitignore

@@ -19,3 +19,4 @@ test-thread-pool
 test-x86-cpuid
 test-xbzrle
 *-test
+qapi-schema/*.test.*

tests/Makefile

@@ -247,10 +247,10 @@ check-tests/test-qapi.py: tests/test-qapi.py
 
 .PHONY: $(patsubst %, check-%, $(check-qapi-schema-y))
 $(patsubst %, check-%, $(check-qapi-schema-y)): check-%.json: $(SRC_PATH)/%.json
-	$(call quiet-command, PYTHONPATH=$(SRC_PATH)/scripts $(PYTHON) $(SRC_PATH)/tests/qapi-schema/test-qapi.py <$^ >$*.out 2>$*.err; echo $$? >$*.exit, "  TEST  $*.out")
-	@diff -q $(SRC_PATH)/$*.out $*.out
-	@diff -q $(SRC_PATH)/$*.err $*.err
-	@diff -q $(SRC_PATH)/$*.exit $*.exit
+	$(call quiet-command, PYTHONPATH=$(SRC_PATH)/scripts $(PYTHON) $(SRC_PATH)/tests/qapi-schema/test-qapi.py <$^ >$*.test.out 2>$*.test.err; echo $$? >$*.test.exit, "  TEST  $*.out")
+	@diff -q $(SRC_PATH)/$*.out $*.test.out
+	@diff -q $(SRC_PATH)/$*.err $*.test.err
+	@diff -q $(SRC_PATH)/$*.exit $*.test.exit
 
 # Consolidated targets