Makefiles named makefile not found anymore on Windows

[Michael Waeber]

Manual:
> If you do not use the ‘-f’ or ‘--file’ flag, the default is to try
GNUmakefile, makefile, and Makefile,
> in that order, and use the first of these three which exists or can be
made.

Since the fix cab353d1 (2014-07-12 Fix defalt_makefiles[] for
MS-Windows.) lower case
makefiles are not found anymore, only -f makefile works.

The filesystem on windows may be case insensitive, but the compare
functions file_exists_p
in dir.c is not.

Proposed patch:
---
read.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/read.c b/read.c
index 6ac66f4..915fa53 100644
--- a/read.c
+++ b/read.c
@@ -247,7 +247,7 @@ read_all_makefiles (const char **makefiles)
{ "GNUmakefile", "Makefile", "SMakefile", 0 };
#else /* !Amiga && !VMS */
#ifdef WINDOWS32
- { "GNUmakefile", "Makefile", "makefile.mak", 0 };
+ { "GNUmakefile", "makefile", "Makefile", "makefile.mak", 0 };
#else /* !Amiga && !VMS && !WINDOWS32 */
{ "GNUmakefile", "makefile", "Makefile", 0 };
#endif /* !Amiga && !VMS && !WINDOWS32 */
---

Best regards, Michael