[libfuzzer] roll icu to ffa4b6704cf5cc9fec9485731f24a05b2ba94bca

Has only one libfuzzer-related change:
    ffa4b67 [libfuzzer] adding //base to more targets.

No changes to the library.

BUG=

Review-Url: https://codereview.chromium.org/2030763003
Cr-Commit-Position: refs/heads/master@{#397813}

DEPS

@@ -144,7 +144,7 @@ deps = {
    Var('chromium_git') + '/external/colorama.git' + '@' + '799604a1041e9b3bc5d2789ecbd7e8db2e18e6b8',
 
   'src/third_party/icu':
-   Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '466129d661caa849d4087b624840b4b2c4ee7d85',
+   Var('chromium_git') + '/chromium/deps/icu.git' + '@' + 'ffa4b6704cf5cc9fec9485731f24a05b2ba94bca',
 
   'src/third_party/hunspell_dictionaries':
    Var('chromium_git') + '/chromium/deps/hunspell_dictionaries.git' + '@' + 'dc6e7c25bf47cbfb466e0701fd2728b4a12e79d5',