[PATCH 1/2] ntdll: Set signal stack before calling getenv.

[Jefferson Carpenter]

Figured out what was causing the Segmentation Fault running the 
exception tests.  Since the AC bit was left on, an exception was thrown 
inside of a glibc function in server_init_thread, and the current TEB 
was mis-identified leading to the crash.  This commit re-orders the code 
in server_init_thread so that the TEB is correctly identified should an 
exception be thrown from inside it.

thanks,
Jefferson