Remove PCH source files

Deprecated in newer versions of Meson.

cardhook/meson.build

@@ -3,10 +3,7 @@ shared_library(
     name_prefix : '',
     include_directories: inc,
     implicit_include_directories : false,
-    c_pch : [
-        '../precompiled.c',
-        '../precompiled.h',
-    ],
+    c_pch : '../precompiled.h',
     dependencies : [
         capnhook.get_variable('hook_dep'),
         capnhook.get_variable('hooklib_dep'),