Fix build of FFmpeg for Windows on ARM.

Author: john-preston

build_ffmpeg_win.sh

@@ -14,8 +14,12 @@ make PREFIX="$FullScriptPath/../local" install
 cd $FullScriptPath/../ffmpeg
 
 export PKG_CONFIG_PATH="$FullExecPath/../local/lib/pkgconfig:$PKG_CONFIG_PATH"
+export PATH="$FullExecPath/../gas-preprocessor:$PATH"
+echo \#\!/bin/sh > $FullExecPath/../gas-preprocessor/cpp
+echo cl \${@:1} >> $FullExecPath/../gas-preprocessor/cpp
+chmod a+x $FullExecPath/../gas-preprocessor/cpp
 
-./configure --prefix=$FullScriptPath/../local \
+./configure --prefix=$FullScriptPath/../local $ARCH_PARAM \
 --toolchain=msvc \
 --extra-cflags="-DCONFIG_SAFE_BITSTREAM_READER=1" \
 --extra-cxxflags="-DCONFIG_SAFE_BITSTREAM_READER=1" \

ffmpeg.patch

@@ -0,0 +1,24 @@
+diff --git a/configure b/configure
+index a89cfa6d95..466e6fe884 100755
+--- a/configure
++++ b/configure
+@@ -6027,8 +6027,8 @@ if enabled_any arm aarch64 || enabled_all ppc altivec && enabled asm; then
+     [ $target_os = "darwin" ] && gaspp_as_type="apple-$gaspp_as_type"
+ 
+     test "${as#*gas-preprocessor.pl}" != "$as" ||
+-    test_cmd gas-preprocessor.pl -arch $arch -as-type $gaspp_as_type -- ${as:=$cc} $as_noop &&
+-        gas="${gas:=gas-preprocessor.pl} -arch $arch -as-type $gaspp_as_type -- ${as:=$cc}"
++    test_cmd ../gas-preprocessor/gas-preprocessor.pl -arch $arch -as-type $gaspp_as_type -- ${as:=$cc} $as_noop &&
++        gas="${gas:=../gas-preprocessor/gas-preprocessor.pl} -verbose -arch $arch -as-type $gaspp_as_type -- ${as:=$cc}"
+ 
+     if ! check_gas ; then
+         as=${gas:=$as}
+@@ -7168,7 +7168,7 @@ if enabled x86; then
+     esac
+ elif enabled_any aarch64 ppc64 && ! enabled bigendian; then
+     case $target_os in
+-        linux)
++        linux|win32)
+             ;;
+         *)
+             disable ffnvcodec cuvid nvdec nvenc