skip neon code in libwebp when neon is explicitly unavailable

third_party/libwebp/dsp/dsp.h

 // Copyright 2011 Google Inc. All Rights Reserved.
 //
 // Use of this source code is governed by a BSD-style license
 // that can be found in the COPYING file in the root of the source
 // tree. An additional intellectual property rights grant can be found
 // in the file PATENTS. All contributing project authors may
 // be found in the AUTHORS file in the root of the source tree.
 // -----------------------------------------------------------------------------
 //
 //   Speed-critical functions.
@@ skipping 142 matching lines @@
     uint8_t* top_dst, uint8_t* bottom_dst, int len);
 
 #ifdef FANCY_UPSAMPLING
 
 // Fancy upsampling functions to convert YUV to RGB(A) modes
 extern WebPUpsampleLinePairFunc WebPUpsamplers[/* MODE_LAST */];
 
 // Initializes SSE2 version of the fancy upsamplers.
 void WebPInitUpsamplersSSE2(void);
 
+#if defined(WEBP_USE_NEON)
 // NEON version
 void WebPInitUpsamplersNEON(void);
+#endif
 
 #endif    // FANCY_UPSAMPLING
 
 // Point-sampling methods.
 typedef void (*WebPSampleLinePairFunc)(
     const uint8_t* top_y, const uint8_t* bottom_y,
     const uint8_t* u, const uint8_t* v,
     uint8_t* top_dst, uint8_t* bottom_dst, int len);
 
 extern const WebPSampleLinePairFunc WebPSamplers[/* MODE_LAST */];
@@ skipping 22 matching lines @@
     uint8_t* rgba, int alpha_first, int w, int h, int stride);
 
 // Same, buf specifically for RGBA4444 format
 extern void (*WebPApplyAlphaMultiply4444)(
     uint8_t* rgba4444, int w, int h, int stride);
 
 // To be called first before using the above.
 void WebPInitPremultiply(void);
 
 void WebPInitPremultiplySSE2(void);   // should not be called directly.
+
+#if defined(WEBP_USE_NEON)
 void WebPInitPremultiplyNEON(void);
+#endif
 
 //------------------------------------------------------------------------------
 
 #if defined(__cplusplus) || defined(c_plusplus)
 }    // extern "C"
 #endif
 
 #endif  /* WEBP_DSP_DSP_H_ */