Cygwin: uname: add host machine tag to sysname.

If the Cygwin dll's architecture is different from the host system's
architecture, append an additional tag that indicates the host system
architecture (the Cygwin dll's architecture is already indicated in
machine).

Signed-off-by: Jeremy Drake <[email protected]>
(cherry picked from commit 7923059)

winsup/cygwin/uname.cc

@@ -51,13 +51,27 @@ uname_x (struct utsname *name)
   __try
     {
       char buf[NI_MAXHOST + 1] ATTRIBUTE_NONSTRING;
+      int n;
 
       memset (name, 0, sizeof (*name));
       /* sysname */
       const char* sysname = get_sysname();
-      __small_sprintf (name->sysname, "%s_%s-%u",
-		       sysname,
-		       wincap.osname (), wincap.build_number ());
+      n = __small_sprintf (name->sysname, "%s_%s-%u",
+			   sysname,
+			   wincap.osname (), wincap.build_number ());
+      if (wincap.host_machine () != wincap.cygwin_machine ())
+	{
+	  switch (wincap.host_machine ())
+	    {
+	      case IMAGE_FILE_MACHINE_ARM64:
+		n = stpcpy (name->sysname + n, "-ARM64") - name->sysname;
+		break;
+	      default:
+		n += __small_sprintf (name->sysname + n, "-%04y",
+				      (int) wincap.host_machine ());
+		break;
+	    }
+	}
       /* nodename */
       memset (buf, 0, sizeof buf);
       cygwin_gethostname (buf, sizeof buf - 1);