bug#8093: etags: Downcase drive letters, for consistency with Emacs proper.

[Francesco Potortì]

>Emacs downcases drive letters when canonicalizing file names on
>Microsoft Windows, but etags upcases them.  etags should be consistent
>with Emacs.  I found this problem by code inspection, because there's
>a macro 'upcase' that normally isn't used in etags.c; its only use is
>in the section of code that upcases drive letters.  Here's a proposed
>patch.

Looks reasonable and I see no compatibility issues.  Please install it.

>2011-02-21  Paul Eggert  <eggert@cs.ucla.edu>
>
>       etags: Downcase drive letters, for consistency with Emacs proper.
>       * etags.c (upcase): Remove; no longer used.
>       (canonicalize_filename): Downcase drive letters.
>
>--- lib-src/etags.c    2011-02-21 16:47:08.883947000 -0800
>+++ /u/cs/fac/eggert/junk/etags.c      2011-02-21 21:21:04.074974000 -0800
>@@ -239,7 +239,6 @@ If you want regular expression support,
>  #define ISLOWER(c)   islower (CHAR(c))
>  
>  #define lowcase(c)   tolower (CHAR(c))
>-#define upcase(c)     toupper (CHAR(c))
>  
>  
>  /*
>@@ -6638,7 +6637,7 @@ filename_is_absolute (char *fn)
>         );
>  }
>  
>-/* Upcase DOS drive letter and collapse separators into single slashes.
>+/* Downcase DOS drive letter and collapse separators into single slashes.
>     Works in place. */
>  static void
>  canonicalize_filename (register char *fn)
>@@ -6648,8 +6647,8 @@ canonicalize_filename (register char *fn
>  
>  #ifdef DOS_NT
>    /* Canonicalize drive letter case.  */
>-  if (fn[0] != '\0' && fn[1] == ':' && ISLOWER (fn[0]))
>-    fn[0] = upcase (fn[0]);
>+  if (fn[0] != '\0' && fn[1] == ':' && ISUPPER (fn[0]))
>+    fn[0] = downcase (fn[0]);
>  
>    sep = '\\';
>  #endif
>
>
>
>
>
>