Roll buildtools 67bf0653b2..db9be6cbc4

  In order to roll GN 15e0e74f..da21696c (r407852:r408676) and pick up
  the following changes:

  da21696c GN: only write targets that should be generated.
  1c27131e [GN] Prefer explicit pool to automatic link_pool for link targets.
  8293c354 GN: don't write separate files for non-binary targets

TBR=dpranke@chromium.org

Review-Url: https://codereview.chromium.org/2193873002
Cr-Commit-Position: refs/heads/master@{#408765}

DEPS

@@ -52,7 +52,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling build tools
   # and whatever else without interference from each other.
-  'buildtools_revision': '67bf0653b2eb9eabd4fc17c4bf2df828e904a558',
+  'buildtools_revision': '1b96e1a41d3d22b24ee8da769c20849e9a002ed2',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.