Define a compatibility macro for platforms that don't have S_ISDIR.

src/espeak.c

 
 #include "speak_lib.h"
 
+#ifndef S_ISDIR
+#define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR)
+#endif
+
 // This version of the command-line speak program uses the
 // libespeak.so.1  library
 

src/libespeak-ng/speak_lib.c

 #include "event.h"
 #include "wave.h"
 
+#ifndef S_ISDIR
+#define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR)
+#endif
+
 unsigned char *outbuf=NULL;
 
 espeak_EVENT *event_list=NULL;

src/speak.c

 #include "voice.h"
 #include "translate.h"
 
+#ifndef S_ISDIR
+#define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR)
+#endif
+
 
 
 extern void Write4Bytes(FILE *f, int value);