[webOS] tune for Cortex-A53

This commit changes architecture CFLAGS on webOS from `-march=armv7-a
-mtune=cortex-a9 -mfpu=neon` to `-mcpu=cortex-a9 -mtune=cortex-a53`
(`-mcpu=cortex-a9` implies `-mfpu=neon-fp16`). This maintains
compatibility with all webOS TVs while optimizing for a newer and more
common core. `-mfloat-abi=softfp` should be kept for ABI compatibility
with system libraries.

tools/depends/configure.ac

@@ -368,7 +368,7 @@ case $host in
       use_cpu="armeabi-v7a"
     fi
     use_toolchain="${use_toolchain:-/usr}"
-    platform_cflags="-fPIC -DPIC -march=armv7-a -mtune=cortex-a9 -mfloat-abi=softfp -mfpu=neon"
+    platform_cflags="-fPIC -DPIC -mcpu=cortex-a9 -mtune=cortex-a53 -mfloat-abi=softfp"
     platform_cxxflags="$platform_cflags -static-libstdc++"
     optimize_flags="-Os"
     platform_ldflags="-Wl,-rpath-link=$prefix/$deps_dir/lib"