Improve error message on foo ?? io::EOF with missing '?' #2036. Fix build on Android

src/compiler/linker.c

@@ -452,7 +452,7 @@ static void linker_setup_android(const char ***args_ref, Linker linker_type, boo
 #elif _WIN32
 	#define ANDROID_HOST_TAG "windows-x86_64"
 #else
-	#error Unknown Host OS
+	error_exit("Unsupported OS for Android host");
 #endif
 
 	if (is_no_pie(compiler.platform.reloc_model)) add_plain_arg("-no-pie");