Fix MSVC compatibility issues

Project now builds in Visual Studio 2017, probably earlier versions
too as long as they support enough of C99.

hook/iohook.c

@@ -1,4 +1,5 @@
 #define WIN32_NO_STATUS
+/* See precompiled.h for more information */
 #include <windows.h>
 #undef WIN32_NO_STATUS
 #include <winternl.h>

hook/meson.build

@@ -1,7 +1,10 @@
 hook_lib = static_library(
     'hook',
     include_directories : inc,
-    c_pch : '../precompiled.h',
+    c_pch : [
+        '../precompiled.c',
+        '../precompiled.h',
+    ],
     sources : [
         'args.c',
         'args.h',