win32: clarify usage of path canonicalization funcs

The path canonicalization functions on win32 are intended to
canonicalize absolute paths; those with prefixes.  In other words,
things start with drive letters (`C:\`), share names (`\\server\share`),
or other prefixes (`\\?\`).

This function removes leading `..` that occur after the prefix but
before the directory/file portion (eg, turning `C:\..\..\..\foo` into
`C:\foo`).  This translation is not appropriate for local paths.

src/win32/path_w32.h

@@ -26,6 +26,9 @@ extern int git_win32_path_from_utf8(git_win32_path dest, const char *src);
  * canonical (always backslashes, never forward slashes) and process any
  * directory entries of '.' or '..'.
  *
+ * Note that this is intended to be used on absolute Windows paths, those
+ * that start with `C:\`, `\\server\share`, `\\?\`, etc.
+ *
  * This processes the buffer in place.
  *
  * @param path The buffer to process

tests/path/win32.c

@@ -203,16 +203,6 @@ void test_path_win32__canonicalize(void)
 	test_canonicalize(L"C:/Foo/Bar", L"C:\\Foo\\Bar");
 	test_canonicalize(L"C:/", L"C:\\");
 
-	test_canonicalize(L"Foo\\\\Bar\\\\Asdf\\\\", L"Foo\\Bar\\Asdf");
-	test_canonicalize(L"Foo\\\\Bar\\\\..\\\\Asdf\\", L"Foo\\Asdf");
-	test_canonicalize(L"Foo\\\\Bar\\\\.\\\\Asdf\\", L"Foo\\Bar\\Asdf");
-	test_canonicalize(L"Foo\\\\..\\Bar\\\\.\\\\Asdf\\", L"Bar\\Asdf");
-	test_canonicalize(L"\\", L"");
-	test_canonicalize(L"", L"");
-	test_canonicalize(L"Foo\\..\\..\\..\\..", L"");
-	test_canonicalize(L"..\\..\\..\\..", L"");
-	test_canonicalize(L"\\..\\..\\..\\..", L"");
-
 	test_canonicalize(L"\\\\?\\C:\\Foo\\Bar", L"\\\\?\\C:\\Foo\\Bar");
 	test_canonicalize(L"\\\\?\\C:\\Foo\\Bar\\", L"\\\\?\\C:\\Foo\\Bar");
 	test_canonicalize(L"\\\\?\\C:\\\\Foo\\.\\Bar\\\\..\\", L"\\\\?\\C:\\Foo");