Update copyright in libquadmath.

libquadmath/ChangeLog

libquadmath/math/cacoshq.c

libquadmath/math/cacosq.c

libquadmath/math/casinhq.c

libquadmath/math/casinq.c

libquadmath/math/catanhq.c

libquadmath/math/catanq.c

libquadmath/math/ccoshq.c

libquadmath/math/cexpq.c

libquadmath/math/cimagq.c

libquadmath/math/clog10q.c

libquadmath/math/clogq.c

libquadmath/math/complex.c

libquadmath/math/conjq.c

libquadmath/math/cosq_kernel.c

libquadmath/math/cprojq.c

libquadmath/math/crealq.c

libquadmath/math/csinhq.c

libquadmath/math/csinq.c

libquadmath/math/csqrtq.c