ffmpeg: fix build failure with gbk encoding (#8812)

Author: choyy

packages/f/ffmpeg/xmake.lua

@@ -137,6 +137,7 @@ package("ffmpeg")
             local configs = {
                 msystem = "MINGW64",
                 base_devel = true,
+                uchardet = true,
             }
             -- @see https://stackoverflow.com/questions/65438878/ffmpeg-build-on-windows-using-msvc-make-fails
             configs.make = true
@@ -271,6 +272,13 @@ package("ffmpeg")
                 if package:is_arch("arm", "arm64") then
                     envs.PATH = path.join(os.programdir(), "scripts") .. path.envsep() .. envs.PATH
                 end
+                -- fix build failure with gbk encoding
+                io.replace("configure", "cp_if_changed $TMPH config.h", [[
+                    config_encodings=$(uchardet $TMPH)
+                    case "$config_encodings" in GB18030|GBK|GB2312)
+                        { printf '\xEF\xBB\xBF'; iconv -f "$config_encodings" -t UTF-8 -c $TMPH; } > config.h;; 
+                    *) cp_if_changed $TMPH config.h;;
+                    esac]], {plain = true})
                 autoconf.install(package, configs, {envs = envs})
             else
                 import("core.base.option")

packages/m/msys2/xmake.lua

@@ -10,6 +10,7 @@ package("msys2")
 
     add_configs("make", {description = "Install gnumake.", default = false, type = "boolean"})
     add_configs("gcc", {description = "Install gcc.", default = false, type = "boolean"})
+    add_configs("uchardet", {description = "Install uchardet.", default = false, type = "boolean"})
     add_configs("diffutils", {description = "Install diffutils.", default = false, type = "boolean"})
     add_configs("base_devel", {description = "Install base-devel.", default = false, type = "boolean"})
     add_configs("mingw64_gcc", {description = "Install mingw64 gcc.", default = false, type = "boolean"})
@@ -41,6 +42,7 @@ package("msys2")
         local packages = {
             "gcc", "make", "diffutils",
             base_devel = "base-devel",
+            uchardet = "mingw-w64-x86_64-uchardet",
             mingw32_gcc = "mingw-w64-i686-gcc",
             mingw32_toolchain = "mingw-w64-i686-toolchain",
             mingw64_gcc = "mingw-w64-x86_64-gcc",