[CMD] GOTO: Fix label parsing.

We note two things, when CMD searches for the corresponding label in the
batch file:
- the first character of the line is always ignored, unless it's a colon;
- the escape caret ^ is supported and interpreted.

Fixes some cmd_winetests.

base/shell/cmd/parser.c

@@ -39,9 +39,6 @@ static const TCHAR *const IfOperatorString[] =
 #define IF_MAX_COMPARISON IF_NEQ
 };
 
-/* These three characters act like spaces to the parser in most contexts */
-#define STANDARD_SEPS _T(",;=")
-
 static BOOL IsSeparator(TCHAR Char)
 {
     return _istspace(Char) || (Char && _tcschr(STANDARD_SEPS, Char));