Add some timestamps in CI build+test output (#6643)

Summary:
When Travis times out, it's hard to determine whether
the last executing thing took an excessively long time or the
sum of all the work just exceeded the time limit. This
change inserts some timestamps in the output that should
make this easier to determine.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6643

Test Plan: CI (Travis mostly)

Reviewed By: anand1976

Differential Revision: D20843901

Pulled By: pdillinger

fbshipit-source-id: e7aae5434b0c609931feddf238ce4355964488b7

.travis.yml

@@ -201,7 +201,7 @@ before_script:
   - ulimit -n 8192
 
 script:
-  - ${CXX} --version
+  - date; ${CXX} --version
   - if [ `command -v ccache` ]; then ccache -C; fi
   - case $TEST_GROUP in
     platform_dependent)

Makefile

@@ -946,7 +946,7 @@ check: all
 	    $(MAKE) T="$$t" TMPD=$(TMPD) check_0;                       \
 	else                                                            \
 	    for t in $(TESTS); do                                       \
-	      echo "===== Running $$t"; ./$$t || exit 1; done;          \
+	      echo "===== Running $$t (`date`)"; ./$$t || exit 1; done;          \
 	fi
 	rm -rf $(TMPD)
 ifneq ($(PLATFORM), OS_AIX)
@@ -959,7 +959,7 @@ endif
 
 # TODO add ldb_tests
 check_some: $(SUBSET)
-	for t in $(SUBSET); do echo "===== Running $$t"; ./$$t || exit 1; done
+	for t in $(SUBSET); do echo "===== Running $$t (`date`)"; ./$$t || exit 1; done
 
 .PHONY: ldb_tests
 ldb_tests: ldb
@@ -1065,7 +1065,7 @@ ifneq ($(PAR_TEST),)
 parloop:
 	ret_bad=0;							\
 	for t in $(PAR_TEST); do		\
-		echo "===== Running $$t in parallel $(NUM_PAR)";\
+		echo "===== Running $$t in parallel $(NUM_PAR) (`date`)";\
 		if [ $(db_test) -eq 1 ]; then \
 			seq $(J) | v="$$t" build_tools/gnu_parallel --gnu --plain 's=$(TMPD)/rdb-{};  export TEST_TMPDIR=$$s;' \
 				'timeout 2m ./db_test --gtest_filter=$$v >> $$s/log-{} 2>1'; \