revert(3p/git): Revert merge of git upstream at v2.26.2

This causes cgit to serve error pages, which is undesirable.

This reverts commit 5229c9b232, reversing
changes made to f2b211131f.

third_party/git/compat/win32/path-utils.c

@@ -1,29 +1,5 @@
 #include "../../git-compat-util.h"
 
-int win32_has_dos_drive_prefix(const char *path)
-{
-	int i;
-
-	/*
-	 * Does it start with an ASCII letter (i.e. highest bit not set),
-	 * followed by a colon?
-	 */
-	if (!(0x80 & (unsigned char)*path))
-		return *path && path[1] == ':' ? 2 : 0;
-
-	/*
-	 * While drive letters must be letters of the English alphabet, it is
-	 * possible to assign virtually _any_ Unicode character via `subst` as
-	 * a drive letter to "virtual drives". Even `1`, or `ä`. Or fun stuff
-	 * like this:
-	 *
-	 *      subst ֍: %USERPROFILE%\Desktop
-	 */
-	for (i = 1; i < 4 && (0x80 & (unsigned char)path[i]); i++)
-		; /* skip first UTF-8 character */
-	return path[i] == ':' ? i + 1 : 0;
-}
-
 int win32_skip_dos_drive_prefix(char **path)
 {
 	int ret = has_dos_drive_prefix(*path);