win32, msvc: fix missing linking against Bcrypt.lib

Fixes this link error:

dict.obj : error LNK2019: unresolved external symbol BCryptGenRandom referenced in function xmlInitRandom

Commit 2e9e758 (dict: Get random seed
from system PRNG, 2023-12-24) updated cmake, but not nmake, correct
this.

win32/Makefile.msvc

@@ -81,6 +81,7 @@ LIBS = $(LIBS) pthreadVC.lib
 !if "$(WITH_MODULES)" == "1"
 LIBS = $(LIBS) kernel32.lib
 !endif
+LIBS = $(LIBS) Bcrypt.lib
 
 # The archiver and its options.
 AR = lib.exe