acscd.m failing

[Daniel J Sebald]

Make check either hangs or takes a very long time on the following:

liboctave/dMatrix.cc ................................... PASS    6/6
scripts/elfun/acosd.m .................................. PASS    3/3
scripts/elfun/acotd.m .................................. PASS    3/3
scripts/elfun/acscd.m ..................................

The acosd.m and acotd.m tests take a fraction of a second while the acscd.m 
test sits for at least a half hour (I broke out of the program) with CPU pegged 
at 100%.  Not sure why cosecant should fail while cotangent is fine.  I tried 
following the fntests.m script but it is somewhat convoluted.

Dan