patch applied (ghc): Fixed the C-- lexer to comply with the standard on hex escape sequences.

[Michael Adams]

Thu May 10 08:03:50 PDT 2007  Michael D. Adams <t-madams at microsoft.com>
  * Fixed the C-- lexer to comply with the standard on hex escape sequences.
  The C-- standard [1] says in Section 3.3.5 "Character literals" that:
   - the hex escape sequence "must contain at least one and
     at most two hexdigits."
   - the octal escape sequence "must contain at least one and
     at most three octdigits."
  
  [1] Norman Ramsey, Simon Peyton Jones, and Christian Lindig.
      "The C-- Language Specication, Version 2.0 ( CVS Revision 1.128 )"
      <http://www.cminusminus.org/extern/man2.pdf>

    M ./compiler/cmm/CmmLex.x -1 +1