fgwrite: memory allocation trouble

[olebole]

The file fgwrite.c is obviously buggy in the memory allocation of slines. slines is globally defined:
https://github.com/iraf-community/fitsutil/blob/a85313c562dd446c2e75f1f8835f971f5354f740/src/fgwrite.c#L112

• main(argc, argv)
  https://github.com/iraf-community/fitsutil/blob/a85313c562dd446c2e75f1f8835f971f5354f740/src/fgwrite.c#L269-L272
  … toc_card() and list_mef() is called indirectly
  https://github.com/iraf-community/fitsutil/blob/a85313c562dd446c2e75f1f8835f971f5354f740/src/fgwrite.c#L303-L306

• toc_card (in, fh, ftype, hd_cards, level, usize) https://github.com/iraf-community/fitsutil/blob/a85313c562dd446c2e75f1f8835f971f5354f740/src/fgwrite.c#L1463-L1468

• list_mef(fd, usize) https://github.com/iraf-community/fitsutil/blob/a85313c562dd446c2e75f1f8835f971f5354f740/src/fgwrite.c#L1585-L1589

This mess goes completely to hell when a reallocation is necessary. Not only is realloc() called with the wrong arguments; sptable was also incremented before (so that it does not point anymore to the allocated memory). And after a realloc, the free(ip) will free the wrong memory.
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