Flush reporters' output streams after writing a benchmark run (#288)
Flush reporters' output streams after writing a benchmark run (#288)

If a reporter's output stream isn't line-buffered (e.g. it's not writing
to a terminal) then it can be some time before a write to it becomes
visible.

This is problematic if, say, you're wanting to use tail -f to view the
file written to via --benchmark_out. Or if the application crashes,
leaving you with no results.

Addressed by flushing the reporters' output streams whenever we invoke
methods that may write to them.
fuchsia-mirror/third_party-benchmark,nickhutchinson/benchmark-cxx03,efcs/benchmark,ntx-/benchmark,mockingbirdnest/benchmark,codygray/benchmark,mockingbirdnest/benchmark,codygray/benchmark,ntx-/benchmark,nickhutchinson/benchmark-cxx03,fuchsia-mirror/third_party-benchmark,disconnect3d/benchmark,everbase/benchmark,efcs/benchmark,nickhutchinson/benchmark,ntx-/benchmark,everbase/benchmark,codygray/benchmark,nickhutchinson/benchmark,nickhutchinson/benchmark-cxx03,efcs/benchmark,nickhutchinson/benchmark,everbase/benchmark,fuchsia-mirror/third_party-benchmark,google/benchmark,mockingbirdnest/benchmark,google/benchmark,disconnect3d/benchmark,efcs/benchmark,everbase/benchmark,mockingbirdnest/benchmark,codygray/benchmark,nickhutchinson/benchmark-cxx03,disconnect3d/benchmark,ntx-/benchmark,disconnect3d/benchmark,google/benchmark,nickhutchinson/benchmark,fuchsia-mirror/third_party-benchmark