Roll GYP 01528c7:3f21260b

This rolls GYP to the latest commit in its repo. The primary
reason for the roll is to pick up the change to the analyzer
logic in 3f21260b, but this picks up a few more changes along the way:

  3f21260b Change analyzer to search for build_targets from supplied targets
  427a0406 Adding framework path mapping for 'copies' action in gyp files.
  b3cef028 AIX's cp command does not support -af which is the default, so use -RPf which achives something similar
  8f3918d7 Promote documents in md-pages branch.
  c3d861c8 ninja win: Suppress noisy messages from link.exe when LTCG is enabled
  265f495c Fix infinite loop on empty variable name.
  741b7f1d Add support for a CPPFLAGS_host environment variable, and update the cflags test to verify it.
  7904ce96 Make the ninja generator handle symlinked paths correctly.

TBR=sky@chromium.org
BUG=542337

Review URL: https://codereview.chromium.org/1415003003

Cr-Commit-Position: refs/heads/master@{#355194}

DEPS

@@ -151,7 +151,7 @@ deps = {
     Var('chromium_git') + '/external/grit-i18n.git' + '@' + '4066463928d64337e6d70046aa4f18b833a2d0e3', # from svn revision 201
 
   'src/tools/gyp':
-    Var('chromium_git') + '/external/gyp.git' + '@' + '01528c7244837168a1c80f06ff60fa5a9793c824',
+    Var('chromium_git') + '/external/gyp.git' + '@' + '3f21260b43401553c37bb28090b65a75577d5b4e',
 
   'src/tools/swarming_client':
    Var('chromium_git') + '/external/swarming.client.git' + '@' +  Var('swarming_revision'),