Set correct .type directive for asm functions.
Set correct .type directive for asm functions.

This is required per binutil manual.
https://sourceware.org/binutils/docs/as/Type.html#Type

Otherwise, runtime SEGV_MAPERR if linked by GNU bfd linker.

BUG=b/20218337
R=wzhong@chromium.org

Review URL: https://webrtc-codereview.appspot.com/47059004

Patch from Wei Zhong <wzhong@chromium.org>.

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#9106}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 80154f6b28f49399f34bc932f54c433856afa840

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