Do not overflow ph_buf

With emojis, phoneme strings can be very long

src/libespeak-ng/dictionary.c

 #include <string.h>
 #include <wctype.h>
 #include <wchar.h>
+#include <assert.h>
 
 #include <espeak-ng/espeak_ng.h>
 #include <espeak-ng/speak_lib.h>
 	int dict_flags0 = 0;
 	MatchRecord match1;
 	MatchRecord match2;
-	char ph_buf[40];
+	char ph_buf[N_PHONEME_BYTES];
 	char word_copy[N_WORD_BYTES];
 	static const char str_pause[2] = { phonPAUSE_NOLINK, 0 };
 
 			phonetic[0] = 0;
 			phoneme_len = 0;
 		} else {
-			strcpy(phonetic, p);
 			phoneme_len = strlen(p);
+			assert(phoneme_len < N_PHONEME_BYTES);
+			strcpy(phonetic, p);
 			p += (phoneme_len + 1);
 		}
 

src/libespeak-ng/translate.h

 
 #define N_WORD_PHONEMES  200 // max phonemes in a word
 #define N_WORD_BYTES     160 // max bytes for the UTF8 characters in a word
+#define N_PHONEME_BYTES  160 // max bytes for a phoneme
 #define N_CLAUSE_WORDS   300 // max words in a clause
 #define N_TR_SOURCE      800 // the source text of a single clause (UTF8 bytes)