Added framework for generating/consuming benchmarking data sets.

This takes the code that was sitting in benchmarks/
already and makes it easier for language-specific
benchmarks to consume.  Future PRs will enhance this
so that the language-specific benchmarks can report
metrics back that will be tracked over time in PerfKit.
diff --git a/configure.ac b/configure.ac
index 33a6c64..d56a704 100644
--- a/configure.ac
+++ b/configure.ac
@@ -180,5 +180,5 @@
 export CXXFLAGS
 AC_CONFIG_SUBDIRS([gmock])
 
-AC_CONFIG_FILES([Makefile src/Makefile conformance/Makefile protobuf.pc protobuf-lite.pc])
+AC_CONFIG_FILES([Makefile src/Makefile benchmarks/Makefile conformance/Makefile protobuf.pc protobuf-lite.pc])
 AC_OUTPUT