Bug 1829512 - Remove check_objdir_backend_reuse. r=glandium,firefox-build-system-reviewers

Tup is no longer a thing, afaict.

Differential Revision: https://phabricator.services.mozilla.com/D176226

moz.configure

@@ -413,27 +413,6 @@ def build_backends(backends):
 set_config("BUILD_BACKENDS", build_backends)
 
 
-@depends(build_environment, build_backends)
-@imports("glob")
-def check_objdir_backend_reuse(build_env, backends):
-    # "Make based" might be RecursiveMake or a hybrid backend, so "Make" is
-    # intentionally vague for use with the substring match below.
-    incompatible_backends = (("Tup", "Make"), ("Make", "Tup"))
-    for backend_file in glob.iglob(
-        os.path.join(build_env.topobjdir, "backend.*Backend")
-    ):
-        for prev, curr in incompatible_backends:
-            if prev in backend_file and any(curr in b for b in backends):
-                die(
-                    "The active objdir, %s, was previously "
-                    "used to build with a %s based backend. "
-                    "Change objdirs (by setting MOZ_OBJDIR in "
-                    "your mozconfig) or clobber to continue.\n",
-                    build_env.topobjdir,
-                    prev,
-                )
-
-
 # Determine whether to build the gtest xul. This happens in automation
 # on Android and Desktop platforms with the exception of:
 #  - Windows PGO, where linking xul-gtest.dll takes too long;