Properly guard imports because they have to be precise on Windows and Darwin...

Properly guard imports because they have to be precise on Windows and Darwin sets __PIC__ automatically

rts/Exception.cmm

@@ -13,7 +13,9 @@
 #include "Cmm.h"
 #include "RaiseAsync.h"
 
+#ifdef __PIC__
 import base_GHCziBase_True_closure;
+#endif
 
 /* -----------------------------------------------------------------------------
    Exception Primitives

rts/HeapStackCheck.cmm

@@ -12,7 +12,9 @@
 
 #include "Cmm.h"
 
+#ifdef __PIC__
 import pthread_mutex_unlock;
+#endif
 
 /* Stack/Heap Check Failure
  * ------------------------

rts/PrimOps.cmm

@@ -27,6 +27,7 @@
 
 #include "Cmm.h"
 
+#ifdef __PIC__
 import __gmpz_init;
 import __gmpz_add;
 import __gmpz_sub;
@@ -46,6 +47,7 @@ import __gmpz_com;
 import base_GHCziIOBase_NestedAtomically_closure;
 import pthread_mutex_lock;
 import pthread_mutex_unlock;
+#endif
 
 /*-----------------------------------------------------------------------------
   Array Primitives

rts/StgMiscClosures.cmm

@@ -12,9 +12,11 @@
 
 #include "Cmm.h"
 
+#ifdef __PIC__
 import pthread_mutex_lock;
 import base_GHCziBase_Czh_static_info;
 import base_GHCziBase_Izh_static_info;
+#endif
 
 /* ----------------------------------------------------------------------------
    Support for the bytecode interpreter.