autotest timings for skipped tests are wrong

[Bruno Haible]

In the testsuite.log, the timings for a skipped test are wrong. Example
from autoconf-2.54c/tests/testsuite.log:

62. acc.at:16: ok       (0m11.570s 0m1.930s)
63. acc.at:17: ok       (0m11.750s 0m2.020s)
64. fortran.at:51: ok (skipped near `fortran.at:51')    (0m11.750s 0m2.020s)
65. acfortran.at:7: ok (skipped near `acfortran.at:7')  (0m11.750s 0m2.020s)
66. acfortran.at:8: ok (skipped near `acfortran.at:8')  (0m11.750s 0m2.020s)
67. acfortran.at:9: ok (skipped near `acfortran.at:9')  (0m11.750s 0m2.020s)
68. acfortran.at:12: ok (0m11.590s 0m2.000s)

Bruno