[bench] Automated benchmarking script (#1906)

* Initial revised automated benchmarking script

* Updating nb_iterations and making loop infinite

* Allowing benchmarking params to be changed from cli

* Renaming old speed test

* Removing numpy dependency for cli

* Change filename and benchmakr on pr level

* Moving build outside loop and adding iterations param

* Moving benchmarking to seperate travis ci test

* Fixing typo and using unused variable

* Added mode labels and updated README accordingly

* Adding new mode 'current' that compraes facebook:dev against current hash

* Typo

* Reverting previous accidental diff

* Typo

* Adding frequency config variable to prevent github from blacklisting

* Added new argument for frequency of fetching new prs

* Updating documentation

tests/Makefile

@@ -237,6 +237,9 @@ poolTests : $(PRGDIR)/util.c $(PRGDIR)/timefn.c poolTests.c $(ZSTDDIR)/common/po
 versionsTest: clean
 	$(PYTHON) test-zstd-versions.py
 
+automated_benchmarking: clean
+	$(PYTHON) automated_benchmarking.py golden-compression 1 current 1 "" 60
+
 checkTag: checkTag.c $(ZSTDDIR)/zstd.h
 	$(CC) $(FLAGS) $< -o $@$(EXT)