Fix Windows includes (don't rely on speech.h).

src/libespeak-ng/speech.c

@@ -32,7 +32,7 @@
 #include <unistd.h>
 #include <wchar.h>
 
-#ifdef PLATFORM_WINDOWS
+#if defined(_WIN32) || defined(_WIN64)
 #include <fcntl.h>
 #include <io.h>
 #include <windows.h>

src/libespeak-ng/voices.c

@@ -26,7 +26,7 @@
 #include <string.h>
 #include <wctype.h>
 
-#ifdef PLATFORM_WINDOWS
+#if defined(_WIN32) || defined(_WIN64)
 #include <windows.h>
 #else
 #include <dirent.h>