code cleanup: next (#1740)

Next bunch of fixes, including unused, non-consts and statics hunting.
Also improves cmake-based installation on MacOS (default data path and
rpath).

src/CMakeLists.txt

 target_link_libraries(
   espeak-ng-bin PRIVATE espeak-ng espeak-ng-config
 )
+set_target_properties(
+  espeak-ng-bin PROPERTIES
+  MACOSX_RPATH ON
+  INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib"
+)
 if (MINGW)
   target_link_options(espeak-ng-bin PRIVATE "-static-libstdc++" "-static")
 endif()

src/libespeak-ng/CMakeLists.txt

 
   espeak_api.c
 )
+set_target_properties(
+  espeak-ng PROPERTIES
+  MACOSX_RPATH ON
+  INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib"
+)
 
 target_include_directories(espeak-ng BEFORE PRIVATE $<TARGET_PROPERTY:espeak-include,INTERFACE_INCLUDE_DIRECTORIES>)
 
   target_compile_definitions(espeak-ng INTERFACE "LIBESPEAK_NG_EXPORT=1")
 endif()
 
+target_compile_definitions(espeak-ng PRIVATE "PATH_ESPEAK_DATA=\"${CMAKE_INSTALL_PREFIX}/share/espeak-ng-data\"")
+
 if (USE_ASYNC)
   target_sources(espeak-ng PRIVATE
     event.c

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,
 #define PRIMARY_LAST     7
 
 static int number_pre;
-static int number_body;
 static int number_tail;
 static int last_primary;
 static int tone_posn;
 	int max_stress_posn2 = 0; // penuntimate syllable of the highest stress
 
 	number_pre = -1; // number of vowels before 1st primary stress
-	number_body = 0;
 	number_tail = 0; // number between tonic syllable and next primary
 	last_primary = -1;
 

src/libespeak-ng/langopts.c

 			break;
 		}
             case V_TUNES: {
-				char names[6][40] = { 0, 0, 0, 0, 0, 0 };
+				char names[6][40] = { {0}, {0}, {0}, {0}, {0}, {0} };
                 n = sscanf(keyValue, "%s %s %s %s %s %s", names[0], names[1], names[2], names[3], names[4], names[5]);
                 translator->langopts.intonation_group = 0;
 

src/libespeak-ng/readclause.c

 	int c1 = ' '; // current character
 	int c2; // next character
 	int cprev = ' '; // previous character
-	int c_next;
+	int c_next = 0;
 	int parag;
 	int ix = 0;
 	int j;

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;

src/libespeak-ng/voices.c

 	char phonemes_name[40] = "";
 	const char *language_type;
 	char buf[sizeof(path_home)+30];
+#if USE_MBROLA
 	char name1[40];
 	char name2[80];
+#endif
 
 	int pitch1;
 	int pitch2;

src/speechPlayer/src/frame.cpp

 
 	public:
 
-	FrameManagerImpl(): curFrame(), curFrameIsNULL(true), sampleCounter(0), newFrameRequest(NULL), lastUserIndex(-1)  {
+	FrameManagerImpl(): newFrameRequest(NULL), curFrame(), curFrameIsNULL(true), sampleCounter(0), lastUserIndex(-1)  {
 		oldFrameRequest=new frameRequest_t();
 		oldFrameRequest->NULLFrame=true;
 	}

src/speechPlayer/src/speechWaveGenerator.cpp

 
 	unsigned int generate(const unsigned int sampleCount, sample* sampleBuf) {
 		if(!frameManager) return 0; 
-		double val=0;
 		for(unsigned int i=0;i<sampleCount;++i) {
 			const speechPlayer_frame_t* frame=frameManager->getCurrentFrame();
 			if(frame) {