Make memory breakpoint faster

Currently, slowmem is used at any time that memory breakpoints are in use.  This commit makes it so that whenever the DBAT gets updated, if the address is overllaping any memchecks, it forces the use of slowmem.  This allows to keep fastmem for any other cases and noticably increases performance when using memory breakpoints.

Source/Core/Core/PowerPC/JitCommon/JitBase.cpp

@@ -46,6 +46,6 @@ bool JitBase::MergeAllowedNextInstructions(int count)
 void JitBase::UpdateMemoryOptions()
 {
   bool any_watchpoints = PowerPC::memchecks.HasAny();
-  jo.fastmem = SConfig::GetInstance().bFastmem;
+  jo.fastmem = SConfig::GetInstance().bFastmem && (UReg_MSR(MSR).DR || !any_watchpoints);
   jo.memcheck = SConfig::GetInstance().bMMU || any_watchpoints;
 }