1. nmake.defs has a syntax error on line 119: `!if' should be `!ifdef'

2. GC_MARK_STACK is 1 by default in config.nt, but this default is broken with the msvc toolchain.  When temacs started to dump, it immediately exited with the message `Invalid function: "DEAD"'. Eli had previously told me (in #12878) to see bug #13070, but it didn't solve the problem. When I tried to change GC_MARK_STACK to 0, Emacs compiled fine. So there must be something wrong about the GCPROS_NOOPS way of marking stack under the vc compiler, maybe someone familiar with the garbage collector can fix it. (MinGW gcc is ok with the default)