sstate: Drop 'SafeDep' code from setscene validation function

I have a feeling this code exists from the time before we had proper
coverage of one sstate task by another task. At that time it was a
"poor" persons version of that idea, we now have much better
code internal to bitbake which handles this.

Worse, this code actually breaks certain rebuild scenarios,
e.g.:

bitbake libtool-cross
bitbake libtool-cross -c cleansstate
rm tmp -rf
bitbake libtool-cross

would fail as binutils-cross wasn't installed from sstate.

The easiest fix is to remove the obsolete/broken code.

[YOCTO #5773]

(From OE-Core master rev: ccad07f35fb7f959e24fd50d04c7d10dd5cf20d0)

(From OE-Core rev: 30d3f06fddea2d8f3537d3415c95d75a6487078c)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/sstate.bbclass

@@ -639,19 +639,12 @@ def setscene_depvalid(task, taskdependees, notneeded, d):
         return x.endswith("-native")
     def isNativeCross(x):
         return x.endswith("-native") or x.endswith("-cross") or x.endswith("-cross-initial")
-    def isSafeDep(x):
-        if x in ["quilt-native", "autoconf-native", "automake-native", "gnu-config-native", "libtool-native", "pkgconfig-native", "gcc-cross", "binutils-cross", "gcc-cross-initial"]:
-            return True
-        return False
+
     def isPostInstDep(x):
         if x in ["qemu-native", "gdk-pixbuf-native", "qemuwrapper-cross", "depmodwrapper-cross", "systemd-systemctl-native", "gtk-update-icon-cache-native"]:
             return True
         return False
 
-    # We can skip these "safe" dependencies since the aren't runtime dependencies, just build time
-    if isSafeDep(taskdependees[task][0]) and taskdependees[task][1] == "do_populate_sysroot":
-        return True
-
     # We only need to trigger populate_lic through direct dependencies
     if taskdependees[task][1] == "do_populate_lic":
         return True