[CPORTLIB]

[CPORTLIB]
- Do a synthesis of all the code I've found concerning initializing COM ports (in kdcom / kddll / kdbg in the kernel and in freeldr). The "// Windows" comments concern the original code for testing the existence of COM ports, inside cportlib, whereas "// ReactOS" comments concern the equivalent existing in our kdcom/kddll/kdbg etc...
- CORRECT THE VIRTUAL PC COM PORT INITIALIZATION !! The problem was, that the current COM port existence test fails on VPC whereas it works well in all other virtual machines. Therefore :
  * I keep the existing testing code in a function called ComPortTest1, this works everywhere but on VPC ;
  * I add a very basic COM port existence test function called ComPortTest2, which basically looks for the scratch register, this works everywhere including on VPC.
  * The COM port existence test consists in the two tests above.

svn path=/trunk/; revision=57776