Added GitHub workflows to run tests

Mostly taken from .travis.yml, biggest changes were around how to get
the status updates to work.

We can't use a token on PRs the same way we could in Travis, so instead
we use a second workflow that checks every pull request for "status"
artifacts, and create the actual statuses in the "workflow_run" event,
where we have full access to repo secrets.

scripts/test.py

@@ -31,7 +31,7 @@ $(foreach target,$(SRC),$(eval $(FLATTEN)))
 -include tests/*.d
 
 .SECONDARY:
-%.test: %.test.o $(foreach f,$(subst /,.,$(SRC:.c=.o)),%.$f)
+%.test: %.test.o $(foreach f,$(subst /,.,$(OBJ)),%.$f)
     $(CC) $(CFLAGS) $^ $(LFLAGS) -o $@
 """
 GLOBALS = """
@@ -771,7 +771,7 @@ if __name__ == "__main__":
         help="Run reentrant tests with simulated power-loss.")
     parser.add_argument('-V', '--valgrind', action='store_true',
         help="Run non-leaky tests under valgrind to check for memory leaks.")
-    parser.add_argument('-e', '--exec', default=[], type=lambda e: e.split(' '),
+    parser.add_argument('-e', '--exec', default=[], type=lambda e: e.split(),
         help="Run tests with another executable prefixed on the command line.")
     parser.add_argument('-d', '--disk',
         help="Specify a file to use for persistent/reentrant tests.")