Don't use NEON optimized code in lpng_v163

The source files required to use the NEON function are not
included so we should not try to reference those symbols.

BUG=477162
TEST=ninja -C out_arm/Release/ pdfium_diff
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1085023003
diff --git a/AUTHORS b/AUTHORS
index cb225ab..c57cb51 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -13,6 +13,7 @@
 Bruce Dawson <brucedawson@chromium.org>
 Chris Palmer <palmer@chromium.org>
 Finnur Thorarinsson <finnur@chromium.org>
+Jiang Jiang <jiangj@opera.com>
 Jochen Eisinger <jochen@chromium.org>
 John Abd-El-Malek <jam@chromium.org>
 Julien Tinnes <jln@chromium.org>
@@ -26,8 +27,8 @@
 Raymes Khoury <raymes@chromium.org>
 Reid Kleckner <rnk@chromium.org>
 Robert Sesek <rsesek@chromium.org>
+Sam Clegg <sbc@chromium.org>
 Thomas Sepez <tsepez@chromium.org>
-Jiang Jiang <jiangj@opera.com>
 
 Foxit Software Inc <*@foxitsoftware.com>
 Google Inc. <*@google.com>
diff --git a/samples/fx_lpng/lpng_v163/pngpriv.h b/samples/fx_lpng/lpng_v163/pngpriv.h
index 7fa3d60..1896538 100644
--- a/samples/fx_lpng/lpng_v163/pngpriv.h
+++ b/samples/fx_lpng/lpng_v163/pngpriv.h
@@ -107,6 +107,11 @@
  * this in $(CC), e.g. "CC=gcc -mfpu=neon", but people who build libpng rarely

  * do this.

  */

+/*

+ * pdfium: This version of libpng does not contain the arm neon optimized code

+ * so we should never try to reference it.

+ */

+#if 0

 #ifndef PNG_ARM_NEON_OPT

    /* ARM NEON optimizations are being controlled by the compiler settings,

     * typically the target FPU.  If the FPU has been set to NEON (-mfpu=neon

@@ -127,6 +132,7 @@
     */

 #  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_neon

 #endif

+#endif

 

 /* Is this a build of a DLL where compilation of the object modules requires

  * different preprocessor settings to those required for a simple library?  If