patch 8.0.0503: endless loop in updating folds with 32 bit ints

Problem:    Endless loop in updating folds with 32 bit ints.
Solution:   Subtract from LHS instead of add to the RHS. (Matthew Malcomson)

patch 8.0.0502: Coverity complains about possible NULL pointer

Problem:    Coverity complains about possible NULL pointer.
Solution:   Add an assert(), let's see if this works on all systems.

patch 8.0.0501: on MS-Windows ":!start" does not work as expected

Problem:    On MS-Windows ":!start" does not work as expected.
Solution:   When creating a process fails try passing the argument to
            ShellExecute().  (Katsuya Hino, closes vim#1570)

patch 8.0.0500: quotestar test is still a bit flaky

Problem:    Quotestar test is still a bit flaky.
Solution:   Add a slower check for v:version.

patch 8.0.0499: taglist() does not prioritize tags for a buffer

Problem:    taglist() does not prioritize tags for a buffer.
Solution:   Add an optional buffer argument. (Duncan McDougall, closes vim#1194)

patch 8.0.0498: two autocmd tests are skipped on MS-Windows

Problem:    Two autocmd tests are skipped on MS-Windows.
Solution:   Make the test pass on MS-Windows. Write the messages in a file
            instead of getting the output of system().

patch 8.0.0497: arabic support is not fully tested

Problem:    Arabic support is not fully tested.
Solution:   Add more tests for the untested functions.  Comment out
            unreachable code.

patch 8.0.0496: insufficient testing for folding

Problem:    Insufficient testing for folding.
Solution:   Add a couple more fold tests. (Dominique Pelle, closes vim#1579)

patch 8.0.0495: quotestar test uses timer instead of timeout

Problem:    The quotestar test uses a timer instead of a timeout, thus it
            cannot be rerun like a flaky test.
Solution:   Remove the timer and add a timeout. (Kazunobu Kuriyama)

patch 8.0.0494: build failure with older compiler on MS-Windows

Problem:    Build failure with older compiler on MS-Windows.
Solution:   Move declaration to start of block.