tests/unix: Add coverage test for uio.resource_stream from frozen str.

tests/unix/extra_coverage.py

@@ -71,3 +71,8 @@ try:
     import frzmpy2
 except ZeroDivisionError:
     print('ZeroDivisionError')
+
+# test loading a resource from a frozen string
+import uio
+buf = uio.resource_stream('frzstr_pkg2', 'mod.py')
+print(buf.read(21))

tests/unix/extra_coverage.py.exp

@@ -104,3 +104,4 @@ frzstr_pkg2.mod
 frzmpy_pkg2.mod
 1
 ZeroDivisionError
+b'# test frozen package'