List sysroots.json as a dependency of exec_script

R=thakis

Change-Id: I14dda5e6735ba059f42f3a0c9b88734d77c2f8f3
Reviewed-on: https://chromium-review.googlesource.com/1006256
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549728}

build/config/posix/BUILD.gn

@@ -80,7 +80,8 @@ config("runtime_library") {
       sysroot_hash =
           exec_script("//build/linux/sysroot_scripts/install-sysroot.py",
                       [ "--print-hash=$current_cpu" ],
-                      "trim string")
+                      "trim string",
+                      [ "//build/linux/sysroot_scripts/sysroots.json" ])
       defines += [ "CR_SYSROOT_HASH=$sysroot_hash" ]
     }
     asmflags += sysroot_flags