Customize x86inc.asm for libvpx

Use settings from vpx_config.asm

Prefix functions with vpx.

Change-Id: I1091d9b063e9f5af0dce554bb636ee894c05dcf7

third_party/x86inc/README.libvpx

@@ -8,3 +8,5 @@ x264/libav's framework for x86 assembly. Contains a variety of macros and
 defines that help automatically allow assembly to work cross-platform.
 
 Local Modifications:
+Get configuration from vpx_config.asm.
+Prefix functions with vpx by default.

third_party/x86inc/x86inc.asm.new

@@ -34,8 +34,10 @@
 ; as this feature might be useful for others as well.  Send patches or ideas
 ; to x264-devel@videolan.org .
 
+%include "vpx_config.asm"
+
 %ifndef private_prefix
-    %define private_prefix x264
+    %define private_prefix vpx
 %endif
 
 %ifndef public_prefix