fix: use C++ 17 compiler for ICU

src/SPC/builder/linux/library/icu.php

@@ -11,7 +11,7 @@ class icu extends LinuxLibraryBase
     protected function build(): void
     {
         $cppflags = 'CPPFLAGS="-DU_CHARSET_IS_UTF8=1  -DU_USING_ICU_NAMESPACE=1  -DU_STATIC_IMPLEMENTATION=1"';
-        $cxxflags = 'CXXFLAGS="-std=c++11"';
+        $cxxflags = 'CXXFLAGS="-std=c++17"';
         $ldflags = 'LDFLAGS="-static"';
         shell()->cd($this->source_dir . '/source')
             ->exec(

src/SPC/builder/macos/library/icu.php

@@ -11,8 +11,10 @@ class icu extends MacOSLibraryBase
     protected function build(): void
     {
         $root = BUILD_ROOT_PATH;
+
+        $cxxflags = 'CXXFLAGS="-std=c++17"';
         shell()->cd($this->source_dir . '/source')
-            ->exec("./runConfigureICU MacOSX --enable-static --disable-shared --prefix={$root}")
+            ->exec("{$cxxflags} ./runConfigureICU MacOSX --enable-static --disable-shared --prefix={$root}")
             ->exec('make clean')
             ->exec("make -j{$this->builder->concurrency}")
             ->exec('make install');