Fix FreeBSD crash after r233837

The FreeBSD debug register access is a little usual, but in any case
different from Linux. As it stands it's not possible to share an
implementation of DR_OFFSET, so revert that part of r233837 and provide
a separate FreeBSD and Linux implementation.

We'll still want a better fix, but this should restore basic
functionality (and the buildbot).

llvm-svn: 234048

lldb/source/Plugins/Process/Utility/RegisterContextFreeBSD_x86_64.cpp

@@ -62,6 +62,9 @@ struct UserArea
     DBG dbg;
 };
 
+#define DR_OFFSET(reg_index) \
+    (LLVM_EXTENSION offsetof(DBG, dr[reg_index]))
+
 //---------------------------------------------------------------------------
 // Include RegisterInfos_x86_64 to declare our g_register_infos_x86_64 structure.
 //---------------------------------------------------------------------------

lldb/source/Plugins/Process/Utility/RegisterContextLinux_x86_64.cpp

@@ -73,6 +73,11 @@ struct UserArea
     uint64_t fault_address; // Control register CR3.
 };
 
+
+#define DR_OFFSET(reg_index) \
+    (LLVM_EXTENSION offsetof(UserArea, dbg) + \
+     LLVM_EXTENSION offsetof(DBG, dr[reg_index]))
+
 //---------------------------------------------------------------------------
 // Include RegisterInfos_x86_64 to declare our g_register_infos_x86_64 structure.
 //---------------------------------------------------------------------------

lldb/source/Plugins/Process/Utility/RegisterInfos_x86_64.h

@@ -27,10 +27,6 @@
      LLVM_EXTENSION offsetof(XSAVE, ymmh[reg_index]) + \
      (32 * reg_index))
 
-#define DR_OFFSET(reg_index) \
-    (LLVM_EXTENSION offsetof(UserArea, dbg) + \
-     LLVM_EXTENSION offsetof(DBG, dr[reg_index]))
-
 #ifdef DECLARE_REGISTER_INFOS_X86_64_STRUCT
 
 // Number of bytes needed to represent a FPR.