Update references to linux_blink_rel in src after rename.

This updates places in the src repo that reference linux_blink_rel,
and should be submitted after http://crrev.com/2187543002.

This change includes those changes which were originally in
http://crrev.com/2182713003, but I changed that CL to only add new
entries to mb_config.pyl.

BUG=590036

Review-Url: https://codereview.chromium.org/2183323002
Cr-Commit-Position: refs/heads/master@{#408156}

cc/PRESUBMIT.py

@@ -338,7 +338,7 @@ def PostUploadHook(cl, change, output_api):
     return []
 
   bots = [
-    'master.tryserver.blink:linux_blink_rel',
+    'master.tryserver.blink:linux_precise_blink_rel',
   ]
 
   results = []

docs/updating_clang.md

@@ -14,7 +14,7 @@
       -b mac_chromium_gyp_dbg &&
     git cl try -m tryserver.chromium.linux -b linux_chromium_chromeos_dbg_ng \
       -b linux_chromium_chromeos_asan_rel_ng -b linux_chromium_msan_rel_ng &&
-    git cl try -m tryserver.blink -b linux_blink_rel
+    git cl try -m tryserver.blink -b linux_precise_blink_rel
 ```
 1.  Commit roll CL from the first step
 1.  The bots will now pull the prebuilt binary, and goma will have a matching