Revert "Define DEV_URANDOM for posix"

This reverts commit 401b2cc8125bc7504f9dfef61ca7955550d361c1.

This broke linux-gpu etc. bot

BUG=

Review URL: https://codereview.chromium.org/541263002

git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/libsrtp@291813 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
diff --git a/libsrtp.gyp b/libsrtp.gyp
index 0071c15..fd6f204 100644
--- a/libsrtp.gyp
+++ b/libsrtp.gyp
@@ -30,7 +30,6 @@
           'HAVE_INTTYPES_H',
           'HAVE_NETINET_IN_H',
           'INLINE=inline',
-          'DEV_URANDOM="/dev/urandom"',
         ],
       }],
       ['OS=="win"', {