[libFuzzer] Increase merge-sigusr sleep after sending signal.
[libFuzzer] Increase merge-sigusr sleep after sending signal.

Test is flaky on buildbot at least partially due to the fuzz target not
exiting before we read its output.

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@360848 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt