Bug 1721514 - Use bootstrapped sysroot when it's there. r=firefox-build-system-reviewers,andi

We do that with everything else (i.e. clang, cbindgen, etc.). We weren't
doing it for sysroots because the support was experimental and the path
was independent of the target, so there was no guarantee that the
sysroot would actually work for the target. As that's not the case
anymore, we can go with more consistency with the bootstrapped
toolchains.

Differential Revision: https://phabricator.services.mozilla.com/D120417

build/moz.configure/toolchain.configure

@@ -943,7 +943,7 @@ def sysroot_path(host_or_target):
 
     sysroot_input = depends(opt, when=when)(lambda x: x)
     bootstrap_sysroot = depends(bootstrap_when, sysroot_input)(
-        lambda bootstrap, input: bootstrap and not input and input.origin == "default"
+        lambda bootstrap, input: bootstrap and not input
     )
 
     @depends(
@@ -951,22 +951,14 @@ def sysroot_path(host_or_target):
         bootstrap_path(
             depends(host_or_target)(lambda t: "sysroot-{}".format(t.toolchain)),
             when=bootstrap_sysroot,
-        ),
-        "--enable-bootstrap",
-        "MOZ_AUTOMATION",
+        )
     )
-    def sysroot_path(sysroot_input, path, bootstrap, automation):
-        bootstrapped = False
+    def sysroot_path(sysroot_input, path):
         if sysroot_input:
             path = sysroot_input[0]
-        elif sysroot_input is not None and sysroot_input.origin != "default":
-            return
-        elif bootstrap or automation:
-            bootstrapped = True
-        if sysroot_input or bootstrapped:
-            if path:
-                log.info("Using %s sysroot in %s", host_or_target_str, path)
-            return namespace(path=path, bootstrapped=bootstrapped)
+        if path:
+            log.info("Using %s sysroot in %s", host_or_target_str, path)
+        return namespace(path=path, bootstrapped=bool(sysroot_input))
 
     return sysroot_path