Attempt to fix build fo Windows by adding module core.system.opt

Author: denizzzka

druntime/mak/COPY

@@ -23,7 +23,8 @@ COPY=\
 	$(IMPDIR)\core\memory.d \
 	$(IMPDIR)\core\runtime.d \
 	$(IMPDIR)\core\simd.d \
-	$(IMPDIR)\core\system.d \
+	$(IMPDIR)\core\system\opt.d \
+	$(IMPDIR)\core\system\package.d \
 	$(IMPDIR)\core\time.d \
 	$(IMPDIR)\core\vararg.d \
 	$(IMPDIR)\core\volatile.d \

druntime/mak/SRCS

@@ -17,7 +17,8 @@ SRCS=\
 	src\core\memory.d \
 	src\core\runtime.d \
 	src\core\simd.d \
-	src\core\system.d \
+	src\core\system\opt.d \
+	src\core\system\package.d \
 	src\core\time.d \
 	src\core\vararg.d \
 	src\core\volatile.d \

druntime/src/core/gc/config.d

@@ -9,7 +9,7 @@ module core.gc.config;
 
 import core.internal.parseoptions;
 import core.stdc.stdio : printf;
-import core.system : Opt;
+import core.system.opt : Opt;
 
 alias Config = Opt.GcConfig;
 

druntime/src/core/system/opt.d

@@ -0,0 +1,11 @@
+///
+module core.system.opt;
+
+package(core):
+
+struct Opt
+{
+    import core.gc.config: ConfigT;
+
+    alias GcConfig = ConfigT!();
+}

druntime/src/core/system.d druntime/src/core/system/package.ddruntime/src/core/system.d renamed to druntime/src/core/system/package.d

@@ -17,10 +17,3 @@ struct Mem
 
     alias allocateOnStack = alloca;
 }
-
-struct Opt
-{
-    import core.gc.config: ConfigT;
-
-    alias GcConfig = ConfigT!();
-}