Avoid passing 0 to realloc in ReadPhondataManifest(compiledata.c). [clang scan-build]

src/include/espeak-ng/espeak_ng.h

 	ENS_NOT_SUPPORTED            = 0x10000AFF,
 	ENS_UNSUPPORTED_PHON_FORMAT  = 0x10000BFF,
 	ENS_NO_SPECT_FRAMES          = 0x10000CFF,
+	ENS_EMPTY_PHONEME_MANIFEST   = 0x10000DFF,
 } espeak_ng_STATUS;
 
 typedef enum {

src/libespeak-ng/compiledata.c

 			free(manifest[ix].name);
 	}
 
+	if (n_lines == 0) {
+		fclose(f);
+		return ENS_EMPTY_PHONEME_MANIFEST;
+	}
+
 	if ((manifest = (NAMETAB *)realloc(manifest, n_lines * sizeof(NAMETAB))) == NULL) {
 		fclose(f);
 		return ENOMEM;

src/libespeak-ng/error.c

 	case ENS_NO_SPECT_FRAMES:
 		strncpy0(buffer, "The spectral file does not contain any frame data", length);
 		break;
+	case ENS_EMPTY_PHONEME_MANIFEST:
+		strncpy0(buffer, "The phoneme manifest file does not contain any phonemes", length);
+		break;
 	default:
 		if ((status & ENS_GROUP_MASK) == ENS_GROUP_ERRNO)
 			strerror_r(status, buffer, length);