Remove x11 from libjingle_media
Remove x11 from libjingle_media

This generates incorrect -lX11 with use_x11=0 in our other build system,
which causes the standalone libjingle_media target to not build.
This patch should fix that. I could remove -lX11 completely, and
libjingle still links fine. So does Chrome if I do the corresponding
change there, so I think this change is safe to make.

BUG=None

Review URL: https://codereview.webrtc.org/1306243013

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#9869}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 0ab8ca83650899e50a42a9064aace2aaa5595c52

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