feat: add Travis CI config and fail-exit in test script

Add .travis.yml with gcc and clang compilers running make && make test.
Modify script/test.py to call sys.exit(1) when any tests fail, ensuring
CI build correctly reports failure status.

.travis.yml

@@ -0,0 +1,5 @@
+language: c
+compiler:
+  - gcc
+  - clang
+script: make && make test

script/test.py

@@ -231,3 +231,6 @@ else:
 for key in sorted(skipped.keys()):
   print ('Skipped ' + color.YELLOW + str(skipped[key]) + color.DEFAULT +
        ' tests: ' + key)
+
+if failed != 0:
+  sys.exit(1)