Fix building mbrowrap.c on Windows.

src/libespeak-ng/mbrowrap.c

 	read_MBR = (PROCISI)GetProcAddress(hinstDllMBR, "read_MBR");
 	close_MBR = (PROCVV)GetProcAddress(hinstDllMBR, "close_MBR");
 	reset_MBR = (PROCVV)GetProcAddress(hinstDllMBR, "reset_MBR");
-	lastError_MBR = (PROCIV)GetProcAddress(hinstDllMBR, "lastError_MBR");
 	lastErrorStr_MBR = (PROCVCI)GetProcAddress(hinstDllMBR, "lastErrorStr_MBR");
 	setNoError_MBR = (PROCVI)GetProcAddress(hinstDllMBR, "setNoError_MBR");
 	setVolumeRatio_MBR = (PROCVF)GetProcAddress(hinstDllMBR, "setVolumeRatio_MBR");
 	init_MBR(mbr_voice_path);
 }
 
-int lastErrorStr_mbrola(char *buffer, int bufsize)
+char *lastErrorStr_mbrola(char *buffer, int bufsize)
 {
 	int result;
 	if (mbr_pid)
 		mbrola_has_errors();
 	result = snprintf(buffer, bufsize, "%s", mbr_errorbuf);
-	return result >= bufsize ? (bufsize - 1) : result;
+	return buffer;
 }
 
 void setNoError_mbrola(int no_error)

src/libespeak-ng/mbrowrap.h

 typedef void (WINAPI *PROCVV)(void);
 typedef void (WINAPI *PROCVI)(int);
 typedef void (WINAPI *PROCVF)(float);
-typedef int (WINAPI *PROCIV)();
+typedef int (WINAPI *PROCIV)(void);
 typedef int (WINAPI *PROCIC)(char *);
 typedef int (WINAPI *PROCISI)(short *, int);
 typedef char * (WINAPI *PROCVCI)(char *, int);
 
 /*
  * Copy into 'buffer' at most 'bufsize' bytes from the latest error
- * message.  This may also contain non-fatal errors from mbrola.  The
- * returned value is the actual number of bytes copied.  When no error
- * message is pending then an empty string is returned.  Consecutive
- * calls to lastErrorStr_MBR() will return the same message unless it
- * is explicitly cleared with resetError_MBR().
+ * message.  This may also contain non-fatal errors from mbrola.  When
+ * no error message is pending then an empty string is returned.
+ * Consecutive calls to lastErrorStr_MBR() will return the same message.
  */
-int (WINAPI *lastErrorStr_MBR)(char *buffer, int bufsize);
+char * (WINAPI *lastErrorStr_MBR)(char *buffer, int bufsize);
 
 /*
  * Tolerance to missing diphones.