expose vp8_deblock

it is used by vp8/encoder/onyx_if.c

fixes:
vp8/encoder/onyx_if.c:5189: warning: implicit declaration of function
‘vp8_deblock’

vp8/common/postproc.c

@@ -274,7 +274,7 @@ static void vp8_deblock_and_de_macro_block(YV12_BUFFER_CONFIG         *source,
 
 }
 
-extern void vp8_deblock(YV12_BUFFER_CONFIG         *source,
+void vp8_deblock(YV12_BUFFER_CONFIG         *source,
                         YV12_BUFFER_CONFIG         *post,
                         int                         q,
                         int                         low_var_thresh,

vp8/common/postproc.h

@@ -87,4 +87,11 @@ void vp8_de_noise(YV12_BUFFER_CONFIG         *source,
                   int                         low_var_thresh,
                   int                         flag,
                   vp8_postproc_rtcd_vtable_t *rtcd);
+
+void vp8_deblock(YV12_BUFFER_CONFIG         *source,
+                 YV12_BUFFER_CONFIG         *post,
+                 int                         q,
+                 int                         low_var_thresh,
+                 int                         flag,
+                 vp8_postproc_rtcd_vtable_t *rtcd);
 #endif