Properly translate ppc64le (#105)

Properly translate ppc64le architecture to the '@platforms//cpu:ppc64le'
constraint value when detected on the host.

Signed-off-by: James Jenkins <James.Jenkins@ibm.com>

host/extension.bzl

@@ -3,8 +3,10 @@ def _translate_cpu(arch):
         return "x86_32"
     if arch in ["amd64", "x86_64", "x64"]:
         return "x86_64"
-    if arch in ["ppc", "ppc64", "ppc64le"]:
+    if arch in ["ppc", "ppc64"]:
         return "ppc"
+    if arch in ["ppc64le"]:
+        return "ppc64le"
     if arch in ["arm", "armv7l"]:
         return "arm"
     if arch in ["aarch64"]: