PATCH: Fix kernel32 GetFullPathName winetest failures.

[KERNEL32]
Modify GetFullPathName to follow Windows® behavior more closely.

Reduces kernel32:path winetests by 4, and fixes all GetFullPathName tests:
http://reactos.org/testman/detail.php?id=1273296
path.c:1619: Test failed: [0] Expected GetLastError() to return 0xdeadbeef, got 87
path.c:1619: Test failed: [1] Expected GetLastError() to return 0xdeadbeef, got 87
path.c:1619: Test failed: [2] Expected GetLastError() to return 0xdeadbeef, got 87
path.c:1619: Test failed: [3] Expected GetLastError() to return 0xdeadbeef, got 87