patch 8.0.0456: typo in MinGW test makefile

Problem:    Typo in MinGW test makefile.
Solution:   Change an underscore to a dot. (Michael Soyka)

patch 8.0.0455: the mode test may hang

Problem:    The mode test may hang in Test_mode(). (Michael Soyka)
Solution:   Set 'complete' to only search the current buffer (as suggested by
            Michael)

patch 8.0.0454: compiler warnings for "always true" comparison

Problem:    Compiler warnings for comparing unsigned char with 256 always
            being true. (Manuel Ortega)
Solution:   Add type cast.

patch 8.0.0453: adding fold marker creates new comment

Problem:    Adding fold marker creates new comment.
Solution:   Use an existing comment if possible. (LemonBoy, closes vim#1549)

patch 8.0.0452: some macros are in lower case

Problem:    Some macros are in lower case.
Solution:   Make a few more macros upper case.

patch 8.0.0451: some macros are in lower case

Problem:    Some macros are in lower case.
Solution:   Make a few more macros upper case. Avoid lower case macros use an
            argument twice.

patch 8.0.0450: v:progpath is not reliably set

Problem:    v:progpath is not reliably set.
Solution:   Read /proc/self/exe if possible. (idea by Michal Grochmal)
            Also fixes missing #if.

patch 8.0.0449: part of fold patch accidentally included

Problem:    Part of fold patch accidentally included.
Solution:   Revert that part of the patch.

patch 8.0.0448: some macros are in lower case

Problem:    Some macros are in lower case, which can be confusing.
Solution:   Make a few lower case macros upper case.

patch 8.0.0447: getting font name does not work on X11

Problem:    Getting font name does not work on X11.
Solution:   Implement gui_mch_get_fontname() for X11.  Add more GUI tests.
            (Kazunobu Kuriyama)