Remove unnecessary crit-sec in WFC3 CTE
Remove unnecessary crit-sec in WFC3 CTE

Resolves #362

This critical section isn't actually needed
since the array access isn't thread overlapping. If it were, the
entire core parallel CTE computation above would not be possible as
it too would need to be within in a crit-sec.

Signed-off-by: James Noss <897e4a798cfa3e609063a099c3c4ac849e1a5839@stsci.edu>

jhunkeler/hstcal,jhunkeler/hstcal,jhunkeler/hstcal