Rename the 'cretonne' crate to 'cretonne-codegen'.

This fixes the next part of #287.

lib/codegen/meta/isa/x86/defs.py

@@ -0,0 +1,28 @@
+"""
+x86 definitions.
+
+Commonly used definitions.
+"""
+from __future__ import absolute_import
+from cdsl.isa import TargetISA, CPUMode
+import base.instructions
+from . import instructions as x86
+from base.immediates import floatcc
+
+ISA = TargetISA('x86', [base.instructions.GROUP, x86.GROUP])
+
+# CPU modes for 32-bit and 64-bit operation.
+X86_64 = CPUMode('I64', ISA)
+X86_32 = CPUMode('I32', ISA)
+
+# The set of floating point condition codes that are directly supported.
+# Other condition codes need to be reversed or expressed as two tests.
+supported_floatccs = [
+        floatcc.ord,
+        floatcc.uno,
+        floatcc.one,
+        floatcc.ueq,
+        floatcc.gt,
+        floatcc.ge,
+        floatcc.ult,
+        floatcc.ule]