arch,x86,mem: Dynamically determine the ISA for Ruby store check

This patch makes the memory system ISA-agnostic by enabling the Ruby
Sequencer to dynamically determine if it has to do a store check. To
enable this check, the ISA is encoded as an enum, and the system
is able to provide the ISA to the Sequencer at run time.

--HG--
rename : src/arch/x86/insts/microldstop.hh => src/arch/x86/ldstflags.hh

src/SConscript

@@ -379,8 +379,20 @@ def makeTheISA(source, target, env):
 
 ''')
 
+    # create defines for the preprocessing and compile-time determination
     for i,isa in enumerate(isas):
         code('#define $0 $1', define(isa), i + 1)
+    code()
+
+    # create an enum for any run-time determination of the ISA, we
+    # reuse the same name as the namespaces
+    code('enum class Arch {')
+    for i,isa in enumerate(isas):
+        if i + 1 == len(isas):
+            code('  $0 = $1', namespace(isa), define(isa))
+        else:
+            code('  $0 = $1,', namespace(isa), define(isa))
+    code('};')
 
     code('''