dbghelp: Improve speed of our hashtable implementation by remembering the last element added to every bucket.

wintrust: Check for the presence of required members of WINTRUST_CERT_INFO rather than requiring callers to be compiled with the same SDK version.

wintrust: Check for the presence of required members of WINTRUST_BLOB_INFO rather than requiring callers to be compiled with the same SDK version.

server: Restart at the head of the wait queue when we woke a thread, since this can modify the queue.

Checking these is somewhat pointless since they should never be
color-renderable according to the FBO spec. This patch also happens to avoid
dereferencing a NULL pointer inside fglrx.