code cleanup: more consts, less statics

src/libespeak-ng/intonation.c

 	0x50, 0x5a, 0x64, 0x70, 0x7c, 0x83, 0x85, 0x88, 0x8a, 0x8c, 0x8e, 0x8f, 0x91, 0x92, 0x93, 0x93
 };
 
-const unsigned char *envelope_data[N_ENVELOPE_DATA] = {
+const unsigned char *const envelope_data[N_ENVELOPE_DATA] = {
 	env_fall,  env_fall,
 	env_rise,  env_rise,
 	env_frise,  env_r_frise,

src/libespeak-ng/synth_mbrola.c

 	MBROLA_TAB *pr;
 	PHONEME_TAB *other_ph;
 	bool found = false;
-	static int mnem;
+	int mnem;
 
 	// control
 	// bit 0  skip the next phoneme

src/libespeak-ng/synthesize.h

 #define PITCHfall   0  // standard pitch envelopes
 #define PITCHrise   2
 #define N_ENVELOPE_DATA   20
-extern const unsigned char *envelope_data[N_ENVELOPE_DATA];
+extern const unsigned char *const envelope_data[N_ENVELOPE_DATA];
 
 extern int formant_rate[];         // max rate of change of each formant
 extern SPEED_FACTORS speed;