Add empty placeholder target for rms_level.*
Add empty placeholder target for rms_level.*

A follow-up CL will move the rms_level.* files into the new target.

Bug: webrtc:11226
Change-Id: I59579b026346f627c0a2739d25f90c12bffbf248
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/171102
Commit-Queue: Sam Zackrisson <b1a93beadfe1d2f7f0106ee02b6ffcdc950aa103@webrtc.org>
Reviewed-by: Per Åhgren <3616c2c8a2c30a769c5419f89b4a810ea6e2f079@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#30840}

TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc