Add ts_crc32_section() helper function

tsfuncs.h

 
 // CRC
 uint32_t        ts_crc32      (uint8_t *data, int data_size);
+uint32_t		ts_crc32_section			(struct ts_section_header *section_header);
 
 // Misc
 int				dec2bcd						(int dec);

tsfuncs_crc.c

 	}
 	return crc;
 }
+
+u_int32_t ts_crc32_section(struct ts_section_header *section_header) {
+	// +3 to include the first 3 bytes before section_length field
+	return ts_crc32(section_header->section_data, section_header->section_length + 3);
+}