utils: Set parser executable path according to USE_SYSTEM make variable

if USE_SYSTEM is not set, the utils make check target will instruct
test-aa-easyprof.py to provide the path of the in-tree parser executable
to aa-easyprof.

If USE_SYSTEM is set, the default parser path (/sbin/apparmor_parser or
the result of `which apparmor_parser`) is used.

The test-aa-easyprof.py script receives the parser path by checking the
__AA_PARSER environment variable. This environment variable is strictly
used by the test script and not any user-facing code so two leading
underscores were used.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: Christian Boltz <apparmor@cboltz.de>
Acked-by: Seth Arnold <seth.arnold@canonical.com>

utils/test/test-aa-easyprof.py

@@ -173,6 +173,13 @@ TEMPLATES_DIR="%s/templates"
         if base:
             self.full_args.append('--base=%s' % base)
 
+        # Check __AA_PARSER, which may be set by the Makefile, to see if
+        # we should use a non-default apparmor_parser path to verify
+        # policy
+        parser = os.getenv('__AA_PARSER')
+        if parser:
+            self.full_args.append('--parser=%s' % parser)
+
         if debugging:
             self.full_args.append('-d')