Change test suite separator character from '-' to ':'.

This allows defining test suites for test-valgrind target without the risk
of e.g. being unable to differentiate the targets test-valgrind (testing
with valgrind) from test-valgrind (testing the valgrind subproject).

mesonbuild/backend/ninjabackend.py

@@ -569,7 +569,7 @@ int dummy;
                 visible_name = 'for top level tests'
             else:
                 visible_name = s
-            elem = NinjaBuildElement(self.all_outputs, 'test-' + s, 'CUSTOM_COMMAND', ['all', 'PHONY'])
+            elem = NinjaBuildElement(self.all_outputs, 'test:' + s, 'CUSTOM_COMMAND', ['all', 'PHONY'])
             elem.add_item('COMMAND', cmd + ['--suite=' + s])
             elem.add_item('DESC', 'Running test suite %s.' % visible_name)
             elem.add_item('pool', 'console')

mesonbuild/coredata.py

@@ -228,8 +228,9 @@ forbidden_target_names = {'clean': None,
                           'PHONY': None,
                           'all': None,
                           'test': None,
+                          'test:': None,
                           'test-valgrind': None,
-                          'test-': None,
+                          'test-valgrind:': None,
                           'benchmark': None,
                           'install': None,
                           'build.ninja': None,