Expose SpectSeqCreate(), SpectSeqDestroy() and LoadSpectSeq() functions for eSpeakNG Java Editor

src/libespeak-ng/spect.c

 	return frame->rms;
 }
 
+#pragma GCC visibility push(default)
 SpectSeq *SpectSeqCreate()
 {
 	SpectSeq *spect = malloc(sizeof(SpectSeq));
 	free(spect->name);
 	free(spect);
 }
+#pragma GCC visibility pop
 
 static float GetFrameLength(SpectSeq *spect, int frame)
 {
 	return (spect->frames[ix]->time - spect->frames[frame]->time) * 1000.0 + adjust;
 }
 
+#pragma GCC visibility push(default)
 espeak_ng_STATUS LoadSpectSeq(SpectSeq *spect, const char *filename)
 {
 	short n, temp;
 	fclose(stream);
 	return ENS_OK;
 }
+#pragma GCC visibility pop