Move default sanitizer options into build/ so that WebRTC can import them.

base/base.gyp

Index: base/base.gyp
diff --git a/base/base.gyp b/base/base.gyp
index 9f60e25e9273f5c2c99828a0f04a20a2447e6a89..59f07f93b556243e66c8ffd86fd958c52e8deda5 100644
--- a/base/base.gyp
+++ b/base/base.gyp
@@ -972,49 +972,6 @@
         ],
       },
     },
-    {
-      'target_name': 'sanitizer_options',
-      'type': 'static_library',
-      'toolsets': ['host', 'target'],
-      'variables': {
-         # Every target is going to depend on sanitizer_options, so allow
-         # this one to depend on itself.
-         'prune_self_dependency': 1,
-         # Do not let 'none' targets depend on this one, they don't need to.
-         'link_dependency': 1,
-       },
-      'sources': [
-        'debug/sanitizer_options.cc',
-      ],
-      'include_dirs': [
-        '..',
-      ],
-      # Some targets may want to opt-out from ASan, TSan and MSan and link
-      # without the corresponding runtime libraries. We drop the libc++
-      # dependency and omit the compiler flags to avoid bringing instrumented
-      # code to those targets.
-      'conditions': [
-        ['use_custom_libcxx==1', {
-          'dependencies!': [
-            '../third_party/libc++/libc++.gyp:libcxx_proxy',
-          ],
-        }],
-        ['tsan==1', {
-          'sources': [
-            'debug/tsan_suppressions.cc',
-          ],
-        }],
-      ],
-      'cflags/': [
-        ['exclude', '-fsanitize='],
-        ['exclude', '-fsanitize-'],
-      ],
-      'direct_dependent_settings': {
-        'ldflags': [
-          '-Wl,-u_sanitizer_options_link_helper',
-        ],
-      },
-    },
   ],
   'conditions': [
     ['OS!="ios"', {