Fix tons of warning such as:

/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpack.c: In function ‘fp_get_param’:
/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpack.c:39:21: warning: passing argument 1 of ‘fp_msg’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]

fp_msg ("Error: internal initialization error\n"); exit (-1);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In file included from /home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpack.c:10:0:
/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpack.h:188:5: note: expected ‘char *’ but argument is of type ‘const char *’
int fp_msg (char *msg);

^~~~~~

/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpack.c:59:12: warning: passing argument 1 of ‘fp_msg’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]

fp_msg ("Error: multiple compression flags\n");
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In file included from /home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpack.c:10:0:
/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpack.h:188:5: note: expected ‘char *’ but argument is of type ‘const char *’
int fp_msg (char *msg);

^~~~~~

/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpack.c:67:12: warning: passing argument 1 of ‘fp_msg’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]

fp_msg ("Error: multiple compression flags\n");

...
....
and

/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpackutil.c:722:13: warning: passing argument 1 of ‘fp_tmpnam’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]

fp_tmpnam("Tmp1", infits, outfits);
          ^~~~~~

/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpackutil.c:123:5: note: expected ‘char *’ but argument is of type ‘const char *’
int fp_tmpnam(char *suffix, char *rootname, char *tmpnam)

^~~~~~~~~

/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpackutil.c:737:13: warning: passing argument 1 of ‘fp_tmpnam’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]

fp_tmpnam("Tmpfile1", "", tempfilename);

...
...
and
/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpackutil.c: In function ‘fp_test_table’:
/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpackutil.c:1913:67: warning: unused parameter ‘outfptr2’ [-Wunused-parameter]
int fp_test_table (fitsfile *infptr, fitsfile *outfptr, fitsfile *outfptr2,

^~~~~~~~

/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpackutil.c:1914:10: warning: unused parameter ‘fpvar’ [-Wunused-parameter]

fpstate fpvar, int *status)
        ^~~~~

/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpackutil.c: In function ‘abort_fpack’:
/home/tstibor/dev/astronomy/kstars/kstars/fitsviewer/fpackutil.c:2367:22: warning: unused parameter ‘sig’ [-Wunused-parameter]
void abort_fpack(int sig)