Fix Clang compilation error on Android in libevent.gyp.

This is part of Chrome for Android upstreaming.

This fixes the following issue we encountered downstream recently due to 'base'
being built for both the host and target but without distinguishing the
compilation flags properly:
third_party/libevent/http.c:561:6: error: implicitly declaring library function 'strlcpy' with type 'unsigned long (char *, const char *, unsigned long)' [-Werror]


Review URL: https://chromiumcodereview.appspot.com/10912095

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@155164 0039d316-1c4b-4281-b951-d872f2087c98

third_party/libevent/libevent.gyp

@@ -36,7 +36,7 @@
             # libevent has platform-specific implementation files.  Since its
             # native build uses autoconf, platform-specific config.h files are
             # provided and live in platform-specific directories.
-            [ 'OS == "linux"', {
+            [ 'OS == "linux" or (OS == "android" and _toolset == "host")', {
               'sources': [ 'epoll.c', 'epoll_sub.c' ],
               'include_dirs': [ 'linux' ],
               'link_settings': {
@@ -47,7 +47,7 @@
                 ],
               },
             }],
-            [ 'OS == "android"', {
+            [ 'OS == "android" and _toolset == "target"', {
               # On android, epoll_create(), epoll_ctl(), epoll_wait() and
               # clock_gettime() are all in libc.so, so no need to add
               # epoll_sub.c and link librt.